PowerPoint 2016 and later versions, include a presenter view which will be activated when your PC or laptop is connected to two monitors or a projector. Presenter view allows you to edit and preview the presentation while the slides are shown to an audience.

The trouble is PowerPoint can lock up in this mode and prevent you from advancing the slides in main presentation, and limit you to working in presenter view. If this problem occurs, make sure that under Slide Show . . . Set up Slide Show, the "Browsed at a kiosk" radial button is not selected. If it is slides will not advance. It's also possible that you may experience the same problem if 'Presented by a speaker' is selected. In this case, simply check off the option at the bottom right of the dialog box: 'Use Presenter View'.