My question is for one iTunes account.
We have two 3Gs that share it and I am about to upgrade my son's line to a 3GS, then me and him are swapping phones.
How do I ensure that my Checkbook register info for my Checkbook app goes to the new phone?
Does iTunes keep application data stored separately by phone, or is it by the app?
And I know that iTunes knows which iPhone is which, but does it do that by phone name we set or the serial numbers?