Hello community,
I'm now in progress of my first course preparation, as below screenshot, I'd like to change the thumbnail image (more attractive images than this first frame of video) to the video I've uploaded per Lecture in every chapters, but cannot find the button or options.

I saw the similar question raised back in year 2019, not sure whether the feature had already beem implemented somewhere, so would like to consult here again.
Thanks a lot for help,
Xiaoqi