People in different locations can view a presentation simultaneously when each person signs in to the presentation and clicks View together at the bottom-right of the screen. Viewers can choose to move from slide to slide on their own or follow along with a presenter who is controlling the presentation.
If you're a collaborator and would like to take control of the presentation, click Take control of presentation at the top-right of your screen. After doing so, viewers will see your current slide displayed above their chat modules. Viewers can then click the Follow the presenter option (also at the top-right of the screen) if they want to follow along in the main portion of their screens. This option is only available to viewers after a collaborator has taken control of the presentation.