To update your password from inside your myTRIBUS profile, first click on "Account Settings" on the main page.

From here, Click "My Account" 

you can update your password by clicking on the "password" field and typing in a new password.

Note: Be sure to save this password in a safe place in case you forget such as a password manager, journal, etc.

After changing the password in this field, click "update" at the bottom of the page and your password will be saved.