Start Web Image Monitor.
For details, see Displaying the Printer Configuration Screens Using a Web Browser.
Point to [Device Management], and then click [Address Book].
Select the user or group.
Click [Change].
Select the [User Authentication] check box in the [Authentication Management] area.
Click [Go to Next].
Click [On] next to [Change Login Password].
Enter the new password in the [Login Password] box.
Enter the new password in the [Confirm Login Password] box.
Click [Go to Next].
Click [OK].
Click [Logout].