The main navigation is held in the main master page template. Navigate to the templates app and find that template. Look for the navigation webpart. In the configuration of the webpart there is a where clause statement. In that box it should have a filter, that filter text will be what you need to look for in your page's form tab.
Most likely if you look at a page's form tab, you will see a dropdown list that says menu group. Its been a while since I've looked at the corporate site but you should be able to go to the Contact page and set that to the same as the Media page.