After you decompile the APK, you need to look for Layout files which define how the UI will be displayed. These are XML files.
You should study the structure of XML, then you should study how android uses layout files. The easiest way to find the correct Layout file IMO, is to find the Picture of the button you are trying to move, and by filename, find which files are referencing to it.
This is your clue
Galaxy Note II - Everything just works, and beautifully.