We use PowerPoint. Find the option in PowerPoint under Set Up Show.
If you do use this feature, and you routinely show a slide to the audience before you Start the Broadcast, you need to pause the first slide in GoTo before anyone starts to speak. If not, the audience will not be able to hear your staff talk before Starting the Broadcast, but they will be able to SEE your words on the screen. Then unpause the screen as you Start the Broadcast.