To change the server admin password follow these steps;
1.) Login to the web control-panel, http://control.branzone.com
2.) Browse to; Voice Servers > YOUR_SERVER > Voice Server Configuration
3.) Once in the configuration page select to edit the "ventrilo_srv.ini" file.
4.) Under the section "Authentication Settings" you will see a text box next to 'AdminPassword' that you can enter the password in to.
Once you have made the required changes and saved the settings you will then need to restart your server for the changes to take affect.