Nayla,
I would strongly suggest not setting the background from the Properties tab. The only reason that settinging exists is if you want a different background color on two different views at the same time. The issue is that it messes up the Color Palette.
Instead, use the Color Palette. That is the little icon to the left of the time controls, that looks like a painter’s palette. You can even create a custom palette by selecting the edit at the bottom of the Palette menu. If this doesn’t work, you will need to reset your configuration (which was messed up using the Background on the Properties tab). This is done through Edit/ Reset to Default Settings.