iOS7 Using own tags for the purchased music
I had this same issue too.  I read on another site to do the following:


Have the song/album/artist labeled how you want it in iTunes.
Sign out of iTunes on your phone/device (settings, iTunes, Apple ID, sign out)
Swipe left on the incorrectly labeled/tagged song within the music app on your phone/device and delete it.
Connect phone/device to iTunes and sync.
After sync is finished you can sign back in to your Apple ID on the phone/device.


I hope this helps cause it works for me. Surely Apple will fix this because it is annoying to have to keep doing this everytime just to have your music labeled how you want it labeled.