You might have come across multiple errors after a simple account password change. This KB article helps you to get it done with ease.
You may change the password via shell/WHM/cPanel, as explained below:-
If you have the shell access, you may run the following cPanel scripts.
/scripts/chpass username passwd /scripts/ftpupdate (you should run this script too to sync the new password in ftp conf files)
1. Login to WHM. URL : https://ipaddress:2087 Username : root or username of the re-seller account, if you are a re-seller. Password : root password or Password of the re-seller account.
2. From the ‘Account Functions’ menu, select ‘Password Modification’.
3. Type the desired password into the Password Entry field.
4. Select the desired account from the Account Selection field.
5. You may not select the Allow MySQL password change checkbox as you do not want to use the new password as your MySQL password.
6. Click Change password to save the new password.
1. Login to cPanel. URL : https://ipaddress:2083 Username : username of the account Password : Password of the account
2. From the ‘Preferences’ menu, select ‘Change Password’.
3. Type the original password under Old Password.
4. Type the desired password into the New Password field.
5. Confirm the new password by entering it into the New Password (again) field.
6. You may not select the Allow MySQL password change checkbox as you do not want to use the new password as your MySQL password.
7. Click Change your password now! to save the new password.
You may also refer to the below url for detailed steps.