To change your email account passwords, use these steps:
1) Log into your account dashboard.
2) On the left-hand side, expand the "Hosting" section, and then choose "My Hosting".
3) Click the "Login" icon (a picture of a person) to the right of your hosted domain name.
This takes you to your hosting control panel, or "cPanel".
4) Go to "Email Accounts"
5) Locate the account that needs to have it's password changed, and click "Manage" next to the email that password needs to be updated for.
6) Enter in the new password (click 'Generate' only if you want a random password to be generated for you otherwise ignore that button) and finally click 'Update Email Settings' to save the password.
If you already know the password, it can be also changed at http://[domain]/webmail or http://webmail.[domain]/.