Prestolocks are guaranteed for life, and they are easy to reset. If you have a new briefcase and want to customise the combination, or if you've inherited a briefcase or bought one second-hand and aren't sure what the combination is, with a little time and persistence you can figure it out and reset the combination.
Use the current combination to open your briefcase. If your briefcase featuring a Prestolock is new, the factory setting for the combination is "0-0-0." If you do not know the current combination, test all possible number combinations until you find one that opens the briefcase.
Write down the three-digit combination you are going to use as the new combination.
Hold the reset button--on the inside of the briefcase, behind the combination lock--down with one finger while you rotate the numbers on the Prestolock until they are set to your new combination.
Let go of the reset button. Rotate the numbers on the combination dial to scramble them.
Test your new combination by entering the combination. If the briefcase unlocks, you have successfully changed the combination.
When you choose a combination, make it easy to remember, but not so easy that someone can guess it easily. Don't use three of the same number.