There is no way to update your banking information once your return has been filed & accepted, the IRS is not going to make changes to returns. For the stimulus money, the IRS is only going by what is on your 2019 return (or 2018 return if you did not file a 2019 return), you will receive a check in the mail when there is no direct deposit information or the information is incorrect on your return you filed.
If the banking information is incorrect or your account is closed, you will automatically be switched to receiving a check in the mail.
