Mine did this for a while too, I had to go into one of the settings screens (don't remember which one, it was a while ago, and I was just messing around with it) but I think you press the MENU button, then go to (screen?) Settings, the option to keep the screen from reverting to the previous screen should be there in a menu, along with the option to change the screen color from green to orange.

I think, anyway. Hopefully I didn't confuse you!