Hi Lisa, you can keep clicking the Undo button (which you can find up the top right of the screen) until you return to Collage mode. Even after you save the collage and exit Ribbet, as long as you’re a registered user, you can open up the collage from your History (on the Library tab) and Undo your way back into Collage mode, where you can change the background color, swap out pictures etc.
