Does one power door lock actuator control all 4 doors and lift gate? Thanks.

Door ajar switch is located in the door latch assembly .. Can try flushing the latch assembly by 'liberally' spraying WD-40 into the latch then close - open door several times .. Repeat as needed... Probably need to do ALL doors the same... I've had pretty good luck doing it that way, plus I use compressed from shop air compressor when needed... Door lock actuator would not cause this problem.

No, each door has an actuator, including the lift gate. Your concern is likely door ajar switch related, as the alarm trips because it thinks a door is open when it isn't. To test, a diagnostic tool with monitoring capability can be used to hook up to the body control module of the vehicle to see which door the car thinks is open when it's really shut. Replace the switch at the related door to solve the problem.