Nothing entered in the current software is sent to the IRS until you hit the "Transmit" button, and that button doesn't exist yet.....and TTX isn't allowing anything to be filed yet at all since there are many changes that have to be made in the forms before the IRS will take anything.
DO NOT attempt to file until the first week in February......until you have every scrap of all your income entered.
SO for now, you are free to navigated back to any and all sections in your tax file and correct any and all entries, since it is currently impossible to have filed anything yet. The tax software "might" allow you to file after the end of the first full week of January (could be delayed further)...but DON'T do it...Dont't hit the Transmit filing button until February at the earliest....otherwise, it will just sit on a server waiting for the IRS to grab it...and the IRS doesn't expect to start until after the 3rd or 4th week in January.
Since whatever you've entered can not possibly have been sent to the IRS yet, you have plenty of time to change everything in your tax file...including how you want to receive your refund.
There a major form changes needed before that final stimulus can be included in the tax forms, and that will stop all filings longer that expected. SO....just don't go thru step 3 in the filing process, and you'll be OK. You can back up and change things at will now, and restart the filing process later.