Zoom - Increase participants viewed in Gallery View
Zoom will permit up to 49 participants in 'gallery view.' There is a setting in your client where you have to increase the max from 25 -> 49.
Minimum requirements are listed here: https://support.zoom.us/hc/en-us/articles/201362323-Changing-the-video-layout-Active-Speaker-View-and-Gallery-View-
And instructions for adjusting from 25->49 are given here: https://support.zoom.us/hc/en-us/articles/201362623