Armstrong Vinyl Floor Yellowing?

I have tried everything to get rid of this yellowing in certain parts of the floor, mainly around the edges. The strangest thing is when it's light out you see these stains. When it starts to get a little darker the stains disappear. I have tried Armstrong's stripper and a few other things. Anyone have any suggestions? It's driving me nuts. I would get another floor, but I'm afraid the same thing would happen.