Wrong album art

I have several IPhones and IPod touch, but I’m only having trouble with the 6 generation of both the iPhone and iPod touch with wrong album art. I download my songs with the right album art , but it is a different album art , when I pull-up song on my device (either one) this only happens with the 6 generation, my other devices ( iPhones & iPod touches of other generations) show correct album art that was downloaded with the songs. I have tried everything I could think of, and everything I could find on the internet, that could help with the problem and nothing has worked, I have noticed that a lot of the information available on the internet doesn’t mention that the problem is only to the 6 generation.

when ever I have a problem with the other generations I find a solution pretty quick. Just can’t find a solution for the problem with the 6 generations.