BBY employee here. Previously if you had a card, you could reapply and get another. Citi no longer allows that...as an existing cardholder, if you try to apply for another account it won't allow it.
Citi recently offered upgrades to Visa from store cards, I'd try giving them a call to see if you can convert. Otherwise, you'd have to close your current account and apply for a new one. If you have great credit (don't know what the threshold is), you will be allowed to choose store or Visa if you are approved. The Visa cards used to have lower APR's, and generally more generous SL's. That's no longer the case either...if you get to choose, they'd both be the same. Visa versions occasionally have bonus cash back offers outside of BBY, and you get cash back on purchases outside of BBY too, so that's a plus.
