Florida Prepaid kicks in first, so that money will be applied to whatever you owe do the university. (I believe UF arranges this automatically in connection with Prepaid) Then when Bright Futures drops (after the drop/add week) it goes to any remaining amounts you owe. If there is excess, it goes into your student’s bank account (assuming you’ve set up the connection to do that as UF recommends.) Not sure about prepaid and Summer B though!
Just as an aside, it doesn’t matter what the prepaid money is slated for. For example, our kid’s prepaid was for “tuition and fees” – Bright Futures does the same. So whatever doesn’t get applied to “tuition and fees” ends up being applied to other school bills like housing.