All doors lock automatically when the lock side is pressed. They unlock when the unlock side is pressed.
Driver's door

Front passenger's door

To lock all the doors from an open front door, press the lock side of the door lock switch and then close the door.
NOTE
When locking the doors this way, be careful not to leave the key inside the vehicle.
Locking, Unlocking with Transmitter
Auto Lock/Unlock FunctionMazda 6 Owners Manual: Dsc on-board diagnosis
On-Board Diagnostic (OBD) Test Description
(See ABS (ABS/TCS) ON-BOARD DIAGNOSIS)
DTC Table
PID/DATA Monitor Table
Active Command Modes Table
...
Mazda 6 Owners Manual: Replacing Exterior Light Bulbs
Headlights (With LED headlights)
Low/High beam bulbs
The LED bulb cannot be replaced as a single unit because it is an integrated
unit.
The LED bulb has to be replaced with the unit. We recommend an Authorized Mazda
Dealer when the replacement is necessary.
Headlights (With halogen headlight ...