Your domain password is the password you use to log on to your CPanel. This
is useful to occasionally do to maximize your site security. You should
always change your password if you think someone else has access
to your account.
To change your domain password:
Click on the Change Password link in the Main Menu area.
Enter your current password in the Old Password field.
Enter your new password in the New Password and New Password
(again) fields.
Click on the Change Your Password Now! button.
Your password has now been changed.
Check
out Ongoing and Completed Sites @ Webmaintainer