Deductions & credits

Depending on the version you are using and whether you already visited the section, the button may say Start, Update,  Edit or Revisit. See the image below.

As far as those questions, the 1098-T input screen, boxes 8 and 9 are the start of it. More eligibility questions come up right after you pass the input screen.

If you need to edit this section, just Edit the Education information section. 

The amount of the non-refundable American Opportunity Credit is limited to your tax liability (line 16 of Form 1040) on you return. TurboTax figures this based on the information you have entered in your tax return.