I was playing with the filter as to crop the screen from showing a watermark above the screen. Perhaps, I did this:
[menubar] -> Video -> Filters -> Crop
After I'm done, The only two buttons at the bottom of the window is "preview" and "close". I also notice there is a panel on the right of the interface showing the active filters. So I assume that "close" would get me out of the window with the filters applied. But I was wrong, It only close the program without applying the settings. If there is a filter you can mess with and you cannot apply it, then whats the point of having a filter anyway?
I'm using windows 10.
Just tested, this should work.
On our YouTube channel Avidemux Demo (https://www.youtube.com/channel/UC7ycUgCIuOlChtpiTFfLTmw/videos?sort=dd&flow=grid&view=0), I've prepared a small demo: How to crop video (Logo) (https://www.youtube.com/watch?v=o3Cd3zfH794), Can you check your steps against this?