Have you already filed? If you've already filed and your return has been accepted (or mailed), it's too late to change your bank account for direct deposit. If you have already filed and it was rejected, you can go back into your account and edit it and fix it, then resubmit it.
If you have not filed yet, here is a link on how to enter in your bank account information into your TurboTax Account:
https://ttlc.intuit.com/questions/3429471-how-do-i-change-my-transferred-direct-deposit-information
