You can reset your PlayOnline Password using the following steps:
2) Select the "PlayOnline / FINAL FANTASY XI Service Accounts" button.
3) Under "Active Service Accounts" and the appropriate FINAL FANTASY XI Service Account, select "Options List."
4) Under "PlayOnline ID Options" towards the bottom of the screen, select "Update PlayOnline Password."
5) Input your new password and re-enter it to confirm. Select "Next" to complete the process.