Mac OS X has a more or less secure place where it stores passwords, certificates, and other security critical data in so-called Keychains. You can inspect and edit this information and change policies with the utility Keychain Access, an application in Applications/Utilities.
Most information is stored in the keychain login, which is accessible with your personal login password. You can create other keychains if you like.
A password for printing to a TUE printer is stored in a item of the category Application and kind Network password. The name is the name of the printer as you have baptized it when you added the printer.