A really weird thing about NFCU joint accounts . . . consider carefully which person you list first. For some incomprehensible IT reason, the second person listed on the account (the "joint" owner) REGARDLESS OF AGE has fewer on-line rights, despite the fact that the legal liability for the account is the same. For example, you cannot pull up old statements. That can be annoying if the second person listed on the account is the one doing the finances.
I have spoken to NFCU about this ad nauseum and they tell me it can't be fixed (at least as of a year ago). The only way to change it is to open an entirely new account. So, I suggest you put your son's name first, if they'll let you just so he has the most flexibility in terms of checking it, etc.