Hi! This article might help. There are a few places to find your AGI.
https://ttlc.intuit.com/community/e-file/help/how-do-i-change-from-mail-to-e-file-in-turbotax-online/00/26985
Take a look at the following TurboTax article for some advice about how and where to find your 2018 AGI for electronic filing:
How do I find last year's AGI?
@bcdb609b6efe