Problems caused by different recording aspect ratios

[tsc119]

I'm having trouble finding information on this. Can someone explain what determines the aspect ratio of a meeting recording? I'm trying to edit a meeting recording (recorded on the cloud) on iMovie, and iMovie is cutting off the frame so that the thumbnail of the speaker next to a shared screen is partially cut off. I went back and looked at the aspect ratio for this Zoom recording, and it shows the dimensions as 1724 × 772.  Then I went back and looked at previous Zoom videos I've edited and the dimensions of the raw Zoom videos vary -- I have some that  are 1760 x 900, some 1724 x 778, and several 640x360.  However, I've never had this problem when editing in iMovie before putting the video on YouTube.

I can make adjustments in iMovie so that the entire Zoom recording is shown in the frame, but that results in a letterbox effect in the edited video, which I don't want.  I'm not clear at all how the Zoom aspect ratio/dimensions are set, and if there' s a way I can pre-set a ratio/dimension so I can avoid this problem to begin with.

Would appreciate any insight/suggestions!

[H45]

Did you ever get a solution for this? I have just had the same issue with a recording my colleagues did specifically to share with a group. And when I brought it into iMovie to add an intro & outro slide their heads got cut off. I'm looking at a number of different video recordings and they all have slightly different aspect ratios. If anyone has any insight on this, I'd appreciate it. Thank you!