Insert the lock's control key into its combination change plug assembly, located just beneath the keyhole. Turn the key counter-clockwise to unscrew the cylinder.
Pull the combination change plug out and set it aside. This reveals the combination change sleeve.
Turn the outside knob one time in a clockwise direction. Continue turning until the knob stops. Release the knob. If done properly, the latch does not retract.
Enter the current combination using the lock's keypad. On some newer models, you may use the factory default combination. This is done by pressing the "2" and "4" key at the same time, then releasing the keys. Then, press and release the "3" key.
Insert the included spanner wrench into the slot where the change plug assembly was. Turn the wrench clockwise until a "click" is felt, indicating that the wrench is in its "Stop" position. Turn the wrench in the other direction, again, until a "click" is felt. Remove the wrench.
Enter your newly chosen combination using the keypad. Turn the outside knob once until it stops. Hold the knob in this position to make sure that the latch has retracted, then release the knob.
Turn the knob clockwise to its "Stop" position. If the latch only retracts when you enter the new combination, the combination was entered successfully.
Screw the combination plug assembly back in, in a clockwise direction, using the control key. Remove the key.