Account Not In This Store Problem

I've updated to iOS 6 in a while, and it's been working fine until this week, where it began to get the ''account is not on this store, please go back to the other store''. thing, when I try to update some apps. I tried going to Settings, then go to iTunes / App Stores, then sign in again and leave settings, and it did not work. Any ideas on how to fix this? Thanks!