I'm having trouble saving my MOV file that I edited using avidemux on win 10. There is no option to save it as a MOV. Interestingly the file was opened successfully but now avidemux insists I use mkv or avi to save it, neither of what I desire to use.
The MP4 muxer will automatically (and silently) switch to MOV mode while keeping the .mp4 extension if the MOV mode is required (i.e. when audio is LPCM). You need a very recent nightly for that.
It is not possible to force usage of MOV muxing mode.