Here is the scenario that i'm wondering about: I've downloaded a good bit of apps from the iTunes App Store using an older iTunes account. Some were free, some were not. I have them synced onto my iPhone. Now, i've got a new iTunes account that I'd like to use on my computer and my iPhone. What will happen when one of the non-free apps are up for an update? Am I going to have to re-sign-in under my old account, since it was the one that I initially purchased the app with?