Corolla Power Door locks working only for front doors

I bought a used toyota corolla. The car has power door locks but only the front doors work with the power locks. The rear doors do not get locked when use the power door lock. What do you think is the problem? Can i fix it myself?

You may have a broken wire running to the back doors/switch.

Use a small screwdriver and carefully pry out the door armrest lock switch.

Once out test for 12v to the switch.

If power is there, the switch may be no good or there is no power going to the door lock actuator and that means removal of the door panel to gain access.

Once accessed, test for power to the actuator and for poor wiring connections or corrosion.