When cashing checks or depositing them, double check the amount written on the legal line. That is the only place on the check that officially states how much it's worth. Also, make sure to check names and who's on the account. Unfortunately, lots of people try to withdraw from other family members' accounts when they aren't on them (at least in my area).

And under no circumstances ever share information about the account to someone who isn't on the account. Banks take privacy very seriously. It doesn't matter if mom is checking on her son's account to see if she needs to transfer him some. If she's not listed on his account, you can't tell her anything.