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: Key reminder switch inspection
1. Disconnect the negative battery cable.
2. Remove the column cover. (See COLUMN COVER REMOVAL/INSTALLATION)
3. Disconnect the key reminder switch connector.
4. Inspect for continuity between the key reminder switch terminals using an
ohmmeter.
If not as specified, replace the key reminder ...
Mazda 6 Owners Manual: Supplemental Restraint System Components
(With Front Passenger Occupant Classification System)
(Without Front Passenger Occupant Classification System)
Driver/Front passenger inflators and air bags
Roll-over sensor (some models), crash sensors, and diagnostic module (SAS
unit).
Seat belt pretensioners
Front air bag sensor ...