Everything is different with the new forms for the 2018 return.
You're not looking in the right place. On the new 2018 Form 1040, the AGI should be on Line 7, about halfway down that first sheet of paper, about 2 inches below the signature section.
The signature block is in the middle of that first printed sheet.
Line 23 is the end of Page 2 (bottom of the first printed sheet). Go back up that page to Line 7 to see AGI.
