You can set a new combination for your ShurLok any time and it is very easy to do. 

Set the combination to the number that opens the shackle

Leave the shackle open.

 

Turn the side change screw 90 degrees clockwise.  Mary is using a paperclip (no tools needed, just use a coin or paperclip).
Change the combination to the number you want for the Shackle.
Turn the change screw back (counter clockwise) 90 degrees

And it is that easy!!! 

Change your combination any time and as often as you want.