After telling TurboTax that I applied my 2017 state tax refund to 2018, I realized that I did not actually do that. How can I modify my answer?

Go to the deductions & Credits page...then scroll down to the "Estimates and Other Taxes Paid" section and expand it....and there is an   " Income Taxes Paid"  to click on ...in there is a section for 2017 State refunds applied to 2018 state taxes....go in there and zero it out.