- Isn't it bizarre that your mother has access to your bank account while you are over 18?! I find that absolutely bizarre and in any case it is a situation you should change as soon as possible in order to prevent you from being stuck in a position where you can't do anything due to not having access to your money.
In many cases if your parent sets up your account while you are still under 18 that "teen" level account holds onto those attributes after you reach the age of majority (though some banks start to charge you monthly for the benefits at that point). Generally all you have to do to convert one over is go into a bank in person and speak with a banker after showing proof you are who you say you are, and ask them to convert it over. Do note that in most cases once you've converted one you will generally need to have/do one of these things to avoid a monthly charge:
1) Have a certain dollar amount constantly in your account (usually around $1500)
2) Make a certain amount of deposits per month (usually around $500)
3) Make at least a certain number of transactions on your card every month (generally around 10, but these generally don't have any limit on the value of the transactions, buying 10 separate $.25 candy bars will prevent the fee just as well as buying 10 $60 video games.)
So to sum it up, in many cases she doesn't actually have your bank account password. Instead what happens is that when she logs in as herself she can access and control your account just like she could when you were still under 18. This can be very useful for some cases (my Mom uses it to drop my bi-weekly chunk of living money into my account for free despite me being a fair distance away from her geographically), but can lead to potential problems if your relationship isn't the best.