I have the AppRadio 3 (SPH-DA210), and I was wondering how to change the background in the main screen. I can change the background in the Apps screen, but I want to change the background in the section that has the radio, disc, settings, etc. Is this possible?

Not possible at the moment. The background files you are looking to change are stored within the firmware file (.hat) that pioneer releases. Currently there is no way that I have found as of yet to modify the internal files of the .hat

If anyone knows how to, please enlighten us