chang direct deposit to apply overpaid tax to estimated tax?

Under "Other Tax Situations" in the section "Additional Tax Payments" is a menu item to "apply refund to next year."

Nobody has filed 2020 yet until the year is over.  Do you mean 2019? Do you want to apply a 2019 refund to next year 2020?  

To apply your federal refund to next year, enter it under

Federal Taxes Tab or Personal (Home & Business)

Other Tax Situations

Additional Tax Payments

Apply Refund to Next Year - Click the Start or Update button

To apply your state refund to next year, enter it under

State Taxes tab

And keep continuing and stepping through the interview about a dozen or more screens and it will finally ask how much you want to apply.  It is probably one of the last questions in the state section.