For the desktop app, you can lock focus on the thumbnail video of a participant in Grid or from the film strip in Stack or Side by side view.

1

Hover over the thumbnail or grid video where you want to lock a participant to, click More More icon, and then select Lock a participant to this location.

More menu opened with Lock a participant to this location highlighted
2

If you know the name of the participant you want to lock to that location, enter it in the search bar or select it from the participant list.

You can lock focus on the first 6 thumbnail videos.

3

To unlock the window, hover over it and click Unlock participant for this location Unlock participants for this location icon.