Changing a user's password is generally preferred to be performed via the cPanel interface as it helps you build a strong password or generate one that meets the strength requirements, however, there may be times when you need to change the password via SSH.
To change the user's passwords via the command line you will use the
passwd command and simply specify the user you wish to modify.
When you update the user's password this will also update the password for the linked-services such as MySQL, FTP, Mail, PostgreSQL and System.
[root@the ~]$ passwd cpuser
Changing password for the user “cpuser” …
Changing password for “cpuser”.
New UNIX password:
Retype new UNIX password:
passwd: The system has successfully updated all authentication tokens.
The system has updated the passwords for the following services: MySQL, ftp, mail, postgresql, system