Users who need access to areas of classified or proprietary information are bombarded with the need to authenticate each request for access. It is not uncommon for some users to have 10, 15, or more passwords. All can vary in specifications for character length, case-sensitivity, and expiration. Some systems keep a history file, preventing users from re-using a password from the past six months.
To defend a beleaguered memory, the user then tries to use a "system" to remember everything. Usually, their system defeats the purpose of a password. Or, the user will go through every password they can think of, only to be locked out of the resource they were trying to access when they fail X number of login attempts.
One method I suggest is to use a password-protected Word document to keep track of all the passwords. Use a table to enter the system, date changed, current password, and one or two past passwords. That way, if the user forgets what password is used on which system, all they have to do is remember the ONE password to the Word document so they can look it up.
In Word, click on File, Tools, Options, and then the Save tab. Enter the password in the "File sharing options for document" section. Make sure you enter a Password to Modify, and update the document each time you change a password.