AA also has a “churn” detection algorithm that I have run afoul of w refundable tix before when my TA booked incorrectly and then cancelled and rebooked certain segments several times. We ultimately had to call AA and get TA to fall on sword and explain their error to allow me to be rebooked on date/time/flight that i needed. If you want to change outbound and leave return, it can be better to instruct TA to make a change as opposed to refunding and rebooking to avoid this churn issue.