In the personal info section, click edit next to your name.  You'll eventually reach a screen with that question.

Later in the education section, you enter it again.  To review or change,  Go through the entire education interview until you reach a screen titled "Your Education Expenses Summary".  Click edit next to the student's name. That should take you to a screen “Here’s your Education Summary”. Click edit next to “Education Information”. You'll eventually reach a screen with that question.

My taxes are pending and it won’t give me that option 

"Pending"?  You mean you already filed?

Then you have to wait to see if it's accepted or rejected.  If rejected, you'll get a chance to fix it.  If accepted, you'll have to wait until your return is fully processed,  then file an amended return.

How to amend https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed

That said, what are you really trying to do? Stating that you are a full time student is not something you file an amended return for.  Halftime or more students qualify for the tuition credit.  Full time student status usually only affects whether yo can be claimed as a dependent.  If you checked the "Someone can claim: You as a dependent" box, that's all that's needed.