Why does the background color not change??
There’s two backgrounds. The menu background starts as a red background on the menus and that will change if you use a different profile as they each have their own color and texture image. You can see this below the puzzle board too if you move the board around.
The puzzle board has a background color as well. That can change by tapping or swiping across the palette. Now what’s important here is the board has a texture image as well. The texture image might be too dark to actually see the color. You can change that texture image by tapping the grid underneath the color palette: