To get the most out of Microsoft Teams on your Macbook, download and install the Teams application. Once you’ve done so, open it, and click on Teams on the left hand side.
Find your profile picture in the upper right-hand corner, shown here:
Click on Settings, shown here:
Find the box that says “Turn on new meeting experience” and add a checkmark, shown here:
Once you have done this, hold Command (⌘) on your keyboard and press Q to quit Teams.
When you next join a Team, you will have the new meeting experience.