1098t question on turbo shows not eligible becase not used to pay school, but it was. how do i change it

You say what  the funds were not (GI benefits or scholarship).  But you don't say what the source of the funds were or how you entered them in TurboTax (TT).

If you're eligible for the credit and TT is not giving it to you, you entered something wrong.  If you can't find the error, delete the student and re-enter the info.

Go through the entire education interview until you reach a screen titled "Your Education Expenses Summary".  Click delete next to the student's name.  You'll then get the "Your Education Expenses Summary" screen again.  Click the "Add a student" button.

There's a new urban myth among college students that says they can get a $1000 from the government just for filing a tax form. For most of them, they simply aren't eligible. A full time unmarried student, under age 24, even if you don't qualify as a dependent, is only eligible for the refundable portion of the American Opportunity Credit if he supports himself by working. You cannot be supporting yourself on parental support, 529 plans or student loans & grants. You usually must have actually paid tuition, not had it paid by scholarships & grants.  It is usually best if the parent claims that credit. 

You cannot claim a credit if you are, or can be, claimed as a dependent by someone else.

Reference: Line 7 instructions for form 8863. https://www.irs.gov/instructions/i8863