After your page has been published you may open the published share.descript.com page to add and adjust the custom thumbnail preview.
In the "Thumbnail" section of your right-hand sidebar, you will have the following options:
- Upload image - allows you to upload your own custom image
- Current frame - allows you to navigate to a point in the timeline of the video and set the visible frame as your preview
- Remove custom thumbnails ('x' button on hover) - Allows you to remove the current custom thumbnail selection.