System is forcing me to take a refund when I want to apply it to tax year 2025. How do I change from a refund to applying it to the next tax year?

To apply part or all of your Federal refund to next year

Federal Taxes Tab or Personal (H&B version)

Other Tax Situations

Additional Tax Payments

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

To apply a state refund I think it will be on one of the last screens before you file state.

Or are you having the Turbo Tax fees deducted from your refund?  Then you have to get Direct Deposit.  Then you can send in an estimated payment for next year.  Or pay the fees upfront with a credit card.