Question

On the one section, it asked for my 2018 AIG, the "learn more" tab said it was section 7 of the 1040

I looked at the wrong box 7 and put in the wrong amount. How do I update that information?

To revisit and correct the 2018 AGI in TurboTax Online:

Sign in and open your return, if you haven't already done so.
From the left menu, select File (tap in the upper-left corner to expand the menu on mobile devices).
Select Start next to Step 3 (if needed, revisit Steps 1 and/or 2 to activate Step 3).
Select I want to e-file.
Continue until you see the place to enter your 2018 AGI.