First, yes, you can change status in the U.S. from O1 or O2 to F1, as well as from B1 to F1. Second, you need to understand that obtaining an O visa is rather difficult (if your sponsor already has an O1, getting an O2 is easier, of course), and more expensive than a B visa. Third, if you plan to work during your Master's studies, F1 would not permit you to do so; but if you will have an O2 and work for your sponsor, you could study part-time without changing status to F1.
Answered on Feb 16th, 2015 at 7:29 PM