1. If AA has cancelled or substantially changed them, you may request a refund to your original form of payment, e.g. credit card.

2. If the flights are then scheduled and presuming that these are standard non-refundable tickets but subject to AA's Covid-19 waiver policy, you should hang tight and do nothing yet. Your flights may well be cancelled or changed between now and November. If that happens, go ahead and request the refund as in #1 . If it does not, simply cancel and take a flight credit.

3. When you are ready to rebook, you will have the use of your credit, but will pay any fare difference. That is and has been crystal clear since Day One of the pandemic waiver. There is absolutely no reason to book for April 2021 at this point. Discounted fares won't likely be released for a good long while and, under the current circumstances, it is doubtful that you will do particularly well by booking more than 30-45 days before departure.

But, as to your bottom line, AA does not permit you to use the credit from your first change to pay for a subsequent change. It is a very generous policy, but not that generous.