Export only works with the slideshow and the temporal view.
Before selecting the export menu, you must set the ratio of the window size and the distribution between the slideshow or the temporal representation and the timeline. The exported file will have the same ratio.
Then, you can export the currently displayed interface:
Current Image menu.
Or the whole animation as images:
As Images menu.
Both export features have the same interface:
Formatof exported image(s): JPEG, PNG, TIFF, or HEIC (MacOS 10.13.4+).
Size: Height of the output image.
Background coloraround the slideshow and/or between the representation and the timeline.