To apply a 2019 Federal refund to next year's 2020 taxes, try this:
- Federal Taxes tab
- Subtab Other Tax Situations.
- Scroll down to Additional Tax Payments.
- One of the subtopics is Apply Refund to Next Year. Click Start.
- It will ask you how much you wish to apply.
I believe any state overpayment (if applicable) that you wish to apply to 2020 would be in your state taxes interview, probably near the end where it asks about refunds, estimates, etc. There are over 40 different states with returns, so it's hard to be specific.
