Okay, here's my issue. I bought a T-Mobile iPhone 5 on April 12. Instead of setting it up as new, I restored it from a backup of my iPod touch. I didn't bother with iTunes because it was having trouble loading. We ended up getting a new computer and we transferred our music and iTunes to a new machine. The other day, I decided to sync my phone on the new machine. It read my iPhone, but when I went to sync, it came up with a message saying that my iPhone was synced to another library, and it gave me the option to erase and sync. Since everything on my iPhone came from either google or icloud, I clicked yes. Well, the only thing that happened was a couple of songs got deleted, and when I'd try to play what was left, it would just scroll sideways and not play. At this point, I decided that it would be best to restore the phone, so I reset my phone. So I reset it, restored it from my latest backup and went about my day. About a half hour later, I noticed that my iPhone was no longer 4G. It was 3G and there was no option that I could see for 4G. So I took it to the T-Mobile store and they said that the carrier update had seemed to fall off. After that was restored, my phone was fine. This still doesn't solve the syncing issue. So here's my question, is this issue happening because I restored the phone from a backup that was synced with my old computer? If I brought the phone back to factory settings and set it up as a new phone, would this solve the problem? I really don't mind having to do that, as long as I know it would work. Plus, what about the carrier settings? If I lose the update, is there a way to update it myself without having to go to the T-Mobile store? Thanks in advance!