How do I change my music album covers on my iPhone?

Hello,

As I was downloading music onto my iPhone 4, all of my music album covers changed. Keep in mind, they are what they're suppose to be on my PC, but changed when it went onto my phone. How can I change it back?

( If you don't know what I mean, my Muse album cover changed to a Bring Me The Horizon album cover when it when onto my phone, but it's not like that on my computer )

Thanks.