For minors, it’s generally required for a parent to co-sign their bank accounts. Once you turn 18, it’s best to establish an account in your name ONLY, so you have sole control of it. It would even be better if you can establish the account at a different bank/credit union than the one the minor account was in, to avoid any inadvertent connections between the previous and new account.
There are a couple reasons for this. It doesn’t take too long to find stories of people who are still using the accounts they had when they were minors who are shocked when their money is suddenly taken away for reasons beyond their control. The parents could have financial problems and either use the money to pay off their debts or the money is seized by the institutions that they owe. There could be disagreements between parents and their kids, so they take the money away as a punishment. Or, it could just be old fashioned greed and the parents decide to just take the money. It doesn’t matter who earned the money that’s in the account. If two people are on it, the money belongs to both parties and the bank isn’t going to stop someone on the account from withdrawing the cash.
Keep in mind also, having your own account does not mean that your parents can’t send you money if you need it. All they need is your account and routing number (the same information that would be on a check) to deposit money into the account. In addition, there are any number of banking apps today they could use to send money to you if you’re still being supported by them. Other excuses may have good intentions at heart, but from a safety and security standpoint, it’s best to establish an independent banking account.