I had to change an award ticket again more recently. Using the IVR, I didn't choose Early Returns (because it's takes too much time) but just chose Existing Reservation.

The agent tried to make me pay a $75 change fee, but I claimed it was an award ticket not within 7 days. She called a Help Desk, and the Help Desk specialist was able to inform her that I should not be charged a change fee.

She changed my award ticket to another flight without a fee.

However I forgot to pay attention to seat assignment which I had paid for, and I lost my seat assignment when getting my flight moved. Usually the agent or myself is observant of the seat (if paid) and the agent is able to find the same seat or similar one on the next flight. I realized this mistake after I hung up the phone. It was just a $3 aisle seat selection not a Stretch Seat.

Atleast I didn't have to pay a change fee, but I may get stuck in a middle seat.