Your banking information cannot be changed after your tax return has been filed and accepted.
Banking information does not go from TT to the IRS until you file your 2020 tax return and it is accepted. The IRS will begin to accept and process 2020 returns at the end of January 2021.
You enter/change banking information in the FILE section before you file your 2020 return. Changing it on the TurboTax site does not do any good until you file your return and the IRS processes your return. If they manage to start sending out stimulus checks before you can change your information, we hope the IRS provides a way for you to change it with the IRS. Right now there are no new guidelines. If your check goes to a wrong or closed account, it will be sent back to the IRS and then the IRS will mail a check to the address on your tax return.
To change your address with the IRS:
CHANGE OF ADDRESS
Note: This takes at least several weeks. Make sure the post office has a forwarding address for your mail.
You can enter your new address on your 2020 tax return, but that will not go to the IRS until you have filed your tax return and it has been accepted. The IRS will not be accepting 2020 returns until at least the end of January.