[pooriaazimi]

I'm sure that's correct, but in this case OP is mistaken. He failed to setup those new iPods correctly - You can use different account for iMessage, Mail and App Store. He must enter his own account in the App Store section of those new Touches and leave iMessage and Main empty (or, create new account for his/her children).

Now, those kids can't see his/her Mail and iMessages, and even if try to buy something from the App Store they can't (they need the parent's password).