I just got a renewed passport too.
On My Account, it says use kiosk or app to scan passport but there is nothing in the app for scanning.
They already have my KTN so passport is redundant?
I didn't scan my previous passport though obviously it's been scanned at kiosks or by the gate agent. Didn't know they store these scans.
You will need to scan it at check-in on your next flight requiring a passport. The App will offer to scan it at T-24.
Nothing you need to do until check-in,