[User 224999]

I'm struggling to get my custom backgrounds to stick when i transfer my setup from pc to android device. At which point in the file structure do i change paths to special, is it:

special://userdata/backgrounds/Kodi 5.jpg

or

special://backgrounds/Kodi 5.jpg

also which xml files need to edited for this to work?

If you use the skin's builtin backup feature it will also transfer your custom backgrounds.
No need to struggle with paths and/or xml files.