OK, so i'm really a naive geezer. I thought when i allowed my 12 yr old son to use the google play credits that came with the nexus 7 that my credit card info was protected. So he downloaded a "free" game -- deer hunter reloaded from Glu. from there he accessed the online site and was able to purchase game credits for $19.99. I get a notice via g mail of the purchase, which was made not through google play but directly from my visa. The only thing I have ever used this visa for at google is to buy the tablet in the first place. How do i protect myself from this kind of accidental use of my card info? My son was unaware of purchasing anything (yes, I believe him).

Hi. We bought the Nexus 7 for our son. at the time he didn't have his own gmail acct, so we used mine to sign up. He has downloaded some apps and books under my name with the $25 credit. I would like to get him his own account for g mail & g play etc. Is there any way to do this without reformating the tablet. Then what about the books & apps linked to my account. I'd appreciate any advice as I'm kind of a geezer (over 50) so this stuff doesn't come natural to me.