How can a guest see the great gallery view with a Mac Desktop Client in a meeting?

Users of Microsoft Teams can choose to see participants in a gallery or a great gallery, if there are enough of them. As regular guest presentator in team meetings I would like to see all the team members 'in the face' when they look at my shared screen. I use the latest version of the Mac-app but I can't figure out what I have to do. 

Who can help me? 

Regards, Herman Post