What have I done wrong?

[ErinShannon]

I've somehow screwed up my Photoshop settings I guess. I use PS CS6 - when I go to File and click on new to make a layout everything seems fine, but when I open up say a paper I want to put on it, it tells me the depths are different and it's going to screw up printing, yada, yada, yada. What have I done? Is it my color mode settings? My resolution settings? I never even pay attention to those settings cause I always had it the same and it just worked. Help!!!