Your banking information cannot be changed after your tax return has been filed and accepted.
You enter/change banking information in the FILE section before you file your 2020 return. The information in your tax return does not go to the IRS until you file the tax return and it has been accepted for processing.
If you have NOT e-filed yet you can change your banking information in the FILE section of the software.
If you already e-filed your 2020 tax return you cannot change your banking information unless the return is rejected when the IRS begins to accept/reject returns on or after February 12. If your return is rejected then you will be able to change the banking information you entered. Then you can re-file the return.
If the return is accepted by the IRS with incorrect banking information, when it goes to the wrong bank account the bank will send the deposit back to the IRS. Then the IRS will mail a check to the address on your tax return.
Here is what the IRS says about entering incorrect banking information