Just a FYI on this avenue of getting into the premium cabin...

Work trip... Bought a Y ticket for $299, F cabin per AA.com was $385.... so a $85 difference for the 2 leg itinerary. Cheap insurance for a confirmed upgrades!

After booking Y, I got the typical upgrade offers in AA app when checking res'y ... they were wanting $85 and $135 for the 2 legs respectively, so I knew calling in to up-fare was a better value.

Called into EXP desk, and was immediately offered the aforementioned upgrade per leg offers. Had to remind the agent that I wasn't paying for a per leg confirmed upgrade, but I wanted to up-fare the entire ticket.
She had to put me on hold to get it resolved, but all was well in the end. Differential between original purchase and AA.com quoted F price was honored.

If you are wanting to use this avenue to get into F, just make sure the agent is quoting you the correct cost for the correct way of completing transaction.

I've had a couple similar experiences lately - much cheaper to upfare rather than buy the "TOD" app/website offers per leg.

Only difference is I've done it through the app or on the website. Just click "change trip", keep the date the same, then scroll through to find the flight(s) you're already on. The higher cabin will be the only choice, click through like a normal purchase. Super easy.

Yup, had done it that way a few times before as well.

This one I had a refundable ticket in Y (for some reason that was what was available when booking, besides BE), and it was then offering refundable F as the online "change trip" option to upfare @ $350+.... didn't need refundable so I called in to go from Refundable Y to non refundable F for the $85-ish price.

Just thought it was interesting that even after specifically asking to upfare, they went right into attempting to sell per leg upgrades. Buyer beware!