Here's my latest find.

Please excuse the direct copy and paste but I wanted to save this for my own notes.
This post is a direct lift from here ...

http://zidroid.com/how-to-fix-extsdcard-mount-issue-on-kitkat-and-lollipop/

Big, big thanks to ZiDroid for helping me with my write to SD card problem.

How to Fix ExtSdCard Mount Issue on KitKat and Lollipop

Since Android 4.4.2 KitKat was released to the Galaxy S4 / Note 3 and other Android devices which support external SD card, more users were having issue with some third-party apps in saving, writing or copying  files to the external SD card due to KitKat 4.4 security which was added by Google.

This is how to fix ExtSdCard Issue on Android KitKat, Lollipop and later for all android devices …

Requirements :

• Rooted Android device running on Android KitKat or Lollipop update.
• Installed ES File Manager or any root files explorer app.

Steps :

Learn how to put Root access on your phone, and do so.
See my post on How do I root My Phone at this link.

Open “ES File Explorer” and press on the top left icon.
Go to Tool > Root Explorer > Mount R/W

Change Path “/” and “/system” from RO to RW.

Go to Local > / Device > system > etc > permissions > and open platform.xml as text in “ES Note Editor”.

Find the following line:

“android.permission.WRITE_EXTERNAL_STORAGE” permission

Change it from :

permission name="android.permission.WRITE_EXTERNAL_STORAGE"
group gid="sdcard_r"
group gid="sdcard_rw"
/permission

To

permission name="android.permission.WRITE_EXTERNAL_STORAGE"
group gid="sdcard_r"
group gid="sdcard_rw"
group gid="media_rw"
/permission

See this pic from ZiDroid that shows the exact format with brackets etc.

Save the changes to the file.

Check the file again and make sure that everything is OK.
After rebooting you will be able to write on the external SD card without any problem.

This has worked for me on my Huawei Mate 7. I like to use the Open Camera app but Android 4.4.2 wouldn't let this app save photos to the external SD card. After this fix, I can now save to the SD card.
.

Can I disable Google Play Services because it chews up my battery ?

 There's a headline that should buy me some attention.

To everybody that asks the same question, can I delete or disable Google Play Services because it chews up 60% of my battery? No you can't and no you don't want to.

So, no you can't, but you can FREEZE it with this app.
(Actually you can, but almost everything on your phone needs it, so don't delete it.)

You must root your phone which is not that scary, however it will void your warranty !
That may be a small price to pay for a much longer battery life.

To root you phone, go to the Kingo Root website and have a read. Make sure it's what you want to do. I did it to remove bloatware and to stop Google Play Services. Download the program, run it, install your phone to your computer via a good USB date cable. That's all there is to it. It's very easy.

http://www.kingoapp.com/

Then go to the Google Play market and install this app.

App Freeze - to freeze unwanted apps on my root access phone.
https://play.google.com/store/apps/details?id=com.smartapp.appfreezer&hl=en

This application can help you to freeze your apps. After the application is frozen, it can not start, it will not run in the background. If you want to use the app again, you can defrost it.
App Freezer can help you to disable memory-intensive applications running in the background, help your device to save memory resources.
App Freezer is only for the root device.

This is only useful if you have rooted your phone and have super user access.
Say goodbye to Google Play Services draining 60% of battery.

Read more on my post "How do I root my phone" and scroll down to the bit about Kingo Root.

http://genuinefreestuff.blogspot.com.au/2015/08/how-do-i-root-my-phone-samsung-galaxy.html

Here's some screenshots for your.
The guilty party ... Google Play Services

And there's lots of components, so expect things to not work if you mess with it.
Touch on Google Play Services to see all the other things running.

Disable it ? Let's see...

Um, maybe not.

 Instead I 'root' my phone and install App Freeze from the market.

Notice that you don't see Google Play Services here, because I froze it.

See ? Gone. I can unfreeze it if I need anything.

The trouble is ... other things stop working.  Gmail, Calendar, Contacts and so on will not like this.

So for most people on most phones, this will NOT be a good solution. It's really only worth doing if you have a minimalist phone for a specific purpose.

This is OK for me because this phone is my offline map phone for travelling. 
All it really has on it is Here maps and an SD card full of downloaded offline maps.

https://play.google.com/store/apps/details?id=com.here.app.maps&hl=en

See my post...

http://genuinefreestuff.blogspot.com.au/2015/08/google-maps-here-maps-offline-maps-for.html

Now that you have Kingo Root on your phone, open up the installed app and look here, pre-installed and system apps

There they are, just waiting to be deleted. Be very careful what you do here because there's no going back if you delete a system app !
Goodbye to Facebook, Soundhound, Vine, Samsung this and that, and every other piece of bloatware.

Cheers. Si.

How do I Root my phone ? Samsung Galaxy S3 GT-I9300

Here's some advice for those who ask, should I root my phone ? No. Don't do it.

Rooting a phone means using programs to grant root access privilege to the phones files and operating system. It's not easy and it's not something to take lightly and you may ruin your phone.

What's root access ? It originates from the development of Unix. Root is the user name or account that by default has access to all commands and files on a Linux or other Unix-like operating system. It is also referred to as the root account, root user and the superuser.

If you don't like how your phone works and certain things are annoying you or you just want it to look and behave differently, put a third party launcher on it like Nova launcher or Go launcher.
A launcher replaces your home-screen, and you can then control how it looks. You can change the themes, colors, scroll effects, removing the app dock bar at the bottom of the phone, and so on.
(Anything in blue is just a highlight, not a link).

Here's some links to Google Play for launchers.
Nova - I use this launcher on all my phones.
https://play.google.com/store/apps/details?id=com.teslacoilsw.launcher&hl=en
Go
https://play.google.com/store/apps/details?id=com.gau.go.launcherex&hl=en
There are plenty more and they're all fun to play with without ruining your phone.

Anyway, all that aside, I put root access on my Samsung Galaxy S3 because it never worked well and then wouldn't boot at all. It also had too much bloatware that ran in the background that I couldn't delete.
I found the original ROM from Samsung and used Odin to flash it onto my phone.
I then used the Kingo website to install root access on my now working phone.
Next is to allow USB debugging.
Then I installed TWRP to control my installations and wipes of ROMs.
Finally I installed the CyanogenMod by copying the downloaded zip file to an SD card and flashing it using TWRP.
It was a long and slow process with many trials and errors.
The end result is good and worth the trouble. Now I can easily change the ROM and try out new ones such as Carbon and AOPK.
I now have much better battery life - two or three days, rather than just one day.
I have complete control of the phone with a lot more options to tweak it in every way.
I have super user / root control to change permissions for apps and to delete any app.

This is what you need to did. This are the steps I followed for a phone that wouldn't even boot.

* Find a good quality USB data cable, not just a recharge cable.

* Charged the phone to full.

* Go to  http://forum.xda-developers.com/  and read everything you can about rooting your phone. I couldn't have done it with all the help in the forums. This post was my guide...

http://forum.xda-developers.com/galaxy-s3/help/guide-odin-flash-guide-t1671969

* Downloaded the original ROM from Samsung.
Mine was called International-GT-i9300-StockRecovery.tar
I found it from a Google search from here...
http://www.drawbycode.com/blog/?p=336    and followed their link to here.
http://stockroms.net/file/GalaxyS3/i9300/stockrecovery/International-GT-i9300-StockRecovery.tar
Go to the bottom of the page and wait 5 seconds, fill in the Captcha and then download the file.

Here's my folder of ROMs and root programs that I have downloaded. It's important to keep it organised.

* Download and installed Odin to your computer from here...
http://odindownload.com/       ... and start it up and minimise it for now.

* Press and hold whatever buttons puts your phone into Download mode.
For me it is Home + Volume Down + Power
Then I see this...

* Press Volume Up to continue to Odin mode.

* Plug your phone in to a USB cable and attach to your computer.  If nothing happens to Odin, you probably don't have a data cable. Change your cable and plug your phone in again and Odin should light up.

* Next I flashed my International-GT-i9300-StockRecovery.tar to my phone.

* Leave all the cables attached and touch nothing, don't even move the phone in case you disturb the connection. Your phone should now reboot into normal mode. Mine did anyway.
Now I have a phone that actually boots to a normal Android existence.

* Go to Settings - About Device and touch on Build Number seven times to enable Developer Mode.

* Go back one level to Developer Options and allow USB debugging.

* Next I Rooted my phone using the Kingo program. This was easy.
Go to  http://www.kingoapp.com/   and download the program.

* Start the program and plug your phone into that same USB data cable.

All done. Your phone is now rooted and you have superuser control to delete bloatware programs and so on.

* Go to the Google Play market and download Root Checker to confirm that you do have Root Access. Pay for the PRO versions to support the dev's.
https://play.google.com/store/apps/details?id=com.joeykrim.rootcheck&hl=en

Run that app on your phone to check.

and also grab SuperSU to allow Super User control of apps.
https://play.google.com/store/apps/details?id=eu.chainfire.supersu

* Next is TWRP to control the installation and Wipe of your custom ROMs.
I found mine here.   https://github.com/TeamWin/android_device_samsung_i9300

OR

Read here ...   https://twrp.me/devices/samsunggalaxys3internationalexynos.html
Download the .tar here ...   https://dl.twrp.me/i9300/

* Go back to Odin.
Shut your phone down.
Put your phone back into download mode which for me is Home + Volume Down + Power
I then press Volume Up to go to Odin mode.

Plug your phone into your computer again and flash that .tar file using the AP key as per the above pictures.

My phone then rebooted itself to normal mode.

* Next step is to boot to Recovery mode. I press Home + Volume UP + Power, note UP, not DOWN this time.  There it is. TWRP at last. This has been my aim for a few days of trial and error and much reading on XDA.

First thing I do is make a backup just in case. I can use this to Recover my phone if I make a mess of things... which I did.
Note that TWRP survives on the phone no matter what you do. You can Wipe and Backup and Recover and TWRP is still there when you press buttons to go to Recovery Mode.

* Now the next tricky bit. Find the correct ROM for you phone along with the correct "gapps".
I put my first ROM on , I think it was Carbon, and I didn't realise that there were no Google Apps in the package.
I worried my at first, but I enjoyed having a good play with the phone and all the settings.

It's quite novel to have a phone stripped back to just an message app, email client and a web browser and not much more. I played with it for about four days before it even needed a charge because there were no other apps running in the background such as Google Play Service.

So you need to fine the ROM which is really just the bare bones operating system and a whole heap of wonderful settings and tweaks, AS WELL AS a package containing the Google Apps to match the ROM, known as a "gapps".

* Now go and search and find and download your ROMs.
I will start with the CyanogenMod for this phone.
Read about it here...
http://www.addictivetips.com/android/cyanogenmod-10-1-complete-review-guide/

Start here ...  http://www.cyanogenmod.org/
Download from here   http://download.cyanogenmod.org/

I used    cm-11-20141115-SNAPSHOT-M12-i9300.zip
From the snapshots... http://download.cyanogenmod.org/?device=i9300&type=snapshot

And the gapps from here ...  http://androidxda.net/gapps/
and used the gapps-kk-20140105-signed.zip  ... kitkat gapps to go with the kitkat CM ROM

* I found the AOKP ROM with gapps here....
http://aokp.co/devices/i9300

* I found the Carbon ROM here. It's a good website. Take a good look around it.
http://carbonrom.org/supported-devices/
My device is this one ... International Galaxy S III (i9300)
So this was my download link... http://carbonrom.org/downloads/?d=OLD/i9300/nightly

and gapps here ... https://basketbuild.com/gapps    and again choose the correct gapps or your flash won't work.
I used kitkat gapps to go with the kitkat ROM.
Android 4.4.x (Minimal Gapps) gapps-kk-20140105-signed.zip

* Copy and paste those ROMs and gapps onto the SD card in your phone or to the internal drive, it doesn't matter which. Make separate folders for each ROM and its gapps so you don't confuse them when you go to flash that new ROM on your phone.

So, boot up your phone in normal mode, plug it into your computer via that USB cable and wait until it comes up as a separate drive, then copy and paste your downloads onto your external SD card or the internal drive.

* Ready ? Once again boot to Recovery mode. I press Home + Volume UP + Power.
I see this...

* Use TWRP to flash the ROM along with the gapps. Select Install. Navigate to where you have those ROMs.
I go up one level to my external SD card.

There's my organised folders with my ROMs and gapps.

This one is the very clever AOKP ROM. This is on my test phone at the moment.

 Swipe to flash. Wait for the reboot into your new ROM.
** Note that if you already have a working operating system (ROM) on your phone, you will need to WIPE first or else you will see a FAIL to install.

If it doesn't work, and it probably won't because you had the wrong gapps for the wrong ROM for your phone, WIPE and start again and read the description on your ROM carefully when you download it. I had a few failures because I didn't read carefully.
TWRP survives the Wipe.
Also try flashing just the ROM without the gapps.

* Here's some screenshots from my AOKP phone.

 You can tweak anything and everything.

I use Nova Launcher from the Google Play market.
This will be my map phone when I travel overseas. I have Here maps and not much else on it. It'll go days without a charge.

** A note on "The SU Binary needs to be updated" messages. I quote from "Superuser"

Superuser is the app that manages what apps on your rooted device have access to su. Apps that are granted su have elevated permissions and can modify just about any part of the system. The app was originally written by zinx, and I took it and made it much more useable. The app consists of two parts, Superuser.apk and the su binary.
Superuser.apk runs as any other app and gives you, the user, a place to see what apps you have allowed or denied, as well as view a log of what apps have used su when.
The su binary is what other apps call when they need superuser rights. The binary checks the database maintained by Superuser.apk to determine if you have already granted rights to the requesting app, and if not tells Superuser.apk to display a prompt asking you for permission.

I see this a fair bit and just press the button that says Continue. No problems so far.

Cheers. Si.

How do I attach a lanyard to my phone - Samsung, Sony, Android, HTC, Huawei, Nokia, Windows, Motorola.

Here's my latest trick.

Remember the good old days when Nokia ruled the phone world and every phone was a Nokia.
I have unashamedly lifted this photo from GSMarena.com from their article "Take a trip down memory lane", which reminded me to write this post. Take a look at the video in that link, it's a great piece of nostalgia.

Every phone looked quite different and interesting. Don't you just miss the excitement of having a phone that looked completely new and unique ?!
Most of them had an eyelet hole to attach a lanyard. Mine all did anyway.

Now days all phones look the same - a flat black slab of polycarbonate. They don't have holes for lanyards either.

Oddly enough, I still want a lanyard on my phone. Especially when I am playing tourist and hanging over the edge of a ship or bridge or high tower to take a picture.

Here's my old faithful Samsung Galaxy S3 in a protective gel case with a lanyard attached.
I use this especially if I am walking my dogs and I either sling my phone around my neck or around my wrist so that I don't drop my phone when the dogs trip me over.

How to do it ?
Buy any standard soft plastic case that you can cut with a sharp knife. Buy a lanyard, or dig out an old one if you kept them in a box somewhere.
Put that case on a chopping board and grab that sharp knife and cut two long narrow slits about 1 cm apart, just wide enough for your lanyard of choice.

Thread a lanyard of choice through the slits and loop it through itself. Done.
Now you can hang your phone from your neck and not drop it when you are balancing on a cliff for a great view.

Cheers. Si.