My son when using his phonics ( he is 5 ) app on the iPad, there was a message which popped up asking if he wants to upgrade to the full version, he pressed yes, I thought it's gonna ask the password, but didn't , I was charged 4.99. It happened for 3 other apps. I need some help to avoid getting charged in the future. I thought every app needs the iTunes password . My son definitely don't know the password for sure. Any suggestions would be appreciated