Passwords for administrators and customers sit in the Database Table auth. If you forget the password for a user and unable to edit any users in the normal user screen, you can directly edit the password via the database. The password uses standard Unix crypt for encryption.
This page assumes you know how to login to your database. The exact way to do it depends on your operating system and the database type. For example, to login to a MySql database in Linux, you would type:
mysql -u <username> -p <database>
The username, databasename and password are all located in jffnms.conf in the /conf/ directory. JFFNMS that comes as a package, such as the Debian package, the file will be located in /etc/jffnms.
The database command to run is
UPDATE auth SET passwd='adpexzg3FUZAk' WHERE usern='admin'
This sets the password for user "admin" to "admin". You can then login and change the password. If it is for a different username, change the value after usern to the name of the user.