How do you control a powerpoint presentation while using the presenter screen?
In order for you to share your PowerPoint presentation you simply choose to run it in a separate window.
First of all, in PowerPoint, go to Slide show, Set up slide show and make sure to choose Present in a window.
That way, when you are presenting, it opens in its own window.
Then - select the Share Screen option and choose Share Entire Window. The next step is to choose that window from the choices when screen sharing.
In the case where you have your presentation, and at the same time need to show things in your browser you can upload the slides to google slides and then present from the tab in Google - that way you can switch between your presentation tab and the other browser tab without having to 'mode switch' in between.