TurboTax automatically selects the federal deduction – standard or itemized – that works best in your favor.
Please see the following TurboTax FAQ to change your deduction type.
https://ttlc.intuit.com/replies/3300919
If the 'jump to' link does not work you can go to Federal Taxes tab > Deductions & Credits sub-tab > Scroll down and click on Wrap up tax breaks > Continue until your are given your deductions type. You can choose to change your deductions type and then click Continue at the bottom of the page.