KitKat 4.4.2 on Samsung Galaxy III

[AC Question]

I just updated my Galaxy SIII and now I get "snapping" when the screen is touched. It does not happen all the time, but quite often. Plus the battery seems to be draining much faster. I would like to go back to Jelly Bean. How can I do that?

 

[RumoredNow]

Is your bootloader unlocked? You would need it unlocked for flashing. If it is not unlocked, then unlocking it will wipe your data. If you will have to wipe out your user data anyway, you should follow the correct (for your phone version) guide for returning to Factory 4.3 from the link below... There are a lot of variations on the S3. Find your appropriate subforum here for your model and check the Rooting, ROMS and Hacks area for your specific model.
Samsung Galaxy S3 - Android Forums at AndroidCentral.com

You could preserve your user data if your bootloader is already unlocked. That means getting the proper 4.3 ROM downloaded to your computer. If you know how to extract it and flash parts via fastboot you would need the bootloader.img, boot.img, recovery.img and system.img flashed. If you don't know how to accomplish this, the Ask a Question area is not the appropriate venue for such in depth tutorials. Go to the Rooting, ROMs and Hacks area for your specific phone model for additional research and possibly open a help thread there.
Samsung Galaxy S3 - Android Forums at AndroidCentral.com