Thumbnails on music on GS3

[Stewby85]

Ok so I had a Evo before I got my GS3 and I think I had this issue there but not sure. Anyway when I play a MP3 on my phone it will show the album cover on some of the music . But on the music files that do not have a cover it shows a picture that I am sure it took out of my pictures somewhere. I really would not mind it so much but the picture it uses is not a picture I would want just anyone to see (Brittany Spears showing her stuff getting out of a Limo) So could somebody tell me how I can change this thumbnail on these files. Thank You so much. LOL