New user interface to the old user interface
Slide the button to the left and then click the Switch Back button in the next window that opens in the app.
Note: If you're registered for the Beta Program, you can't switch back to the old interface. To unsubscribe, open the ClickShare Desktop App, go to settings and toggle the Beta Program off.
Old user interface to the new user interface
In the App, click Switch to the new version and then click Switch Now.
Note: The old interface is being gradually phased out and will eventually be completely replaced by the new interface.