Also, their waivers depend on when you bought the ticket. I'll assume you purchased prior to March 2020.
They currently do not have waivers in place for May travel. If your travel was in April, they would allow fee free changes, but would collect on any fare difference.
If they end up cancelling your flight, they will issue you a voucher for future travel.
The combination of the above two points has apparently left MANY people in the position of having their flight cancelled, and then having AM ask them for thousands of dollars to rebook onto alternate flights.