Be cautious changing flights with checked bags
As others may have mentioned, be very skeptical when AA staff tells you they can move your checked luggage to a different flight.
At the LAX First Class Lounge, the woman behind the desk wanted to move me from AA2447 to AA2450. I had just arrived on QF11 which was 90min late and the reason I scheduled a late connection. When I cautioned her that I had checked bags, she told me that there was plenty of time to locate and move them to the earlier flight. With that assurance, I let her move me.
When I arrived at DFW, my bags were nowhere to found, I went to talk to AA staff. I explained to him that AA had proactively moved me to an earlier flight even though I had checked bags. I was being grilled when I last saw my bags and if they had ever arrived at LAX. I informed him that I picked up my bags at LAX for customs and handed them off to be re-checked. I discovered that they were still on my earlier flight.
Lesson learned is not to allow AA to place you on an earlier flight if you have checked luggage. Amusingly, a year ago on a connection from MIA to DFW. AA had placed my bags on an earlier flight without notifying me.