This feature prevents all power windows from operating, except the driver's power window. Keep this switch in the locked position while children are in the vehicle.
Locked position (button depressed):
Only the driver's power window can be operated.
Unlocked position (button not depressed):
All power windows on each door can be operated.

NOTE
When the power window lock switch is in the locked position, the light on each power window switch, except for the driver's power window switch, turns off. The light may be difficult to see depending on the surrounding brightness.
Operating the Power Windows
Moonroof (Some models)Mazda 6 Owners Manual: Front door lock actuator inspection
Door Lock Actuator
1. Disconnect the front door lock actuator connector.
2. Apply battery positive voltage to the front door lock actuator terminals
and inspect the operation of the front door lock actuator.
If not as specified, replace the front door lock actuator.
With double locking ...
Mazda 6 Owners Manual: Rear door lock actuator inspection
Door Lock Actuator
1. Disconnect the front door lock actuator connector.
2. Apply battery positive voltage to the front door lock actuator terminals
and inspect the operation of the front door lock actuator.
If not as specified, replace the front door lock actuator.
With double locking ...