Background glitch

Every time I upload a custom background, it always switches to a black or red or blue  background or another background. Help?

Basically, you can only have a background on the first section of a level. If you try to have a background in one level with multiple sections (sections being the courses you link together with the pipes or doors or whatever) it will only have it on the first section, as soon as you go to the second, it glitches and chooses the wrong background or color like you said (in my experience it also does sprite sheets). There is no fix for it so you just have to work around it. If it's glitching on the first section of the level then I really don't know what's going on.