You can’t update your bank information if your return has already been filed, and it's been accepted by the government. If you have a refund coming, you'll receive a refund check instead of a direct deposit.
If your return has been rejected in the efile system, or you have not yet filed yet, you can update your information in TurboTax by going to the File tab and updating your information before submitting the return.
If you entered a valid but incorrect account number that’s not yours, you’re most likely fine. Most banks won't deposit tax refunds into accounts where the names don't match. You can try calling the IRS to stop the direct deposit if your return hasn't been posted to their system yet.
Please see the TurboTax Help article What if I entered the wrong bank account for direct deposit? for more guidance.