I was told by both the website and the help-line operator that I had to change it at my work location. The reason given was that if we were offered the opportunity at our work location to change password, then we wouldn't be given the opportunity at home.
We have to change ours at the store. I was told they expire after 90 days and you have to go in and get a new one. I've had to reset mine twice but my new password has worked for over 5 months now.