How do I change Office Chat preferences

From your Windows desktop app:
  1. Click on the “gear” icon right next to the search bar on the app window.
  2. On the preferences dialog box that opens and then on the “General” tab. This tab has most of the common preference settings, like starting office chat client on Windows startup, play notification sounds, etc.
  3. If you are connecting to the internet from behind a proxy server, then use the “Proxy” tab to enter the proxy server details.