Change the thumbnail picture for a video
You can pause a video at any time and use the picture that appears on the paused screen as the video's thumbnail picture.
On the home screen, click the Media icon > Videos icon.
Play a video.
If the media controls don't appear at the bottom of the screen, click the trackpad.
When the video shows the picture that you want to use as the thumbnail picture, click the icon.
key > Set Video Thumbnail.