Changing the default background color while working

I want to export some images I’m working on, but the background where there’s blank space seems to be stuck at black instead of the white I want, and I can’t find an option to change it. Where do I go to adjust the default background color?

The easiest thing to do is drop in a color card effect

http://docs.toonboom.com/help/animate/#HAR/Stage/019_Effects/032_H2_Colour_Card_.html