Sometimes the thumbnail that Facebook chooses for your video can be a bit unflattering. If you don’t like your face you can change the thumbnail automatically selected by Facebook.
Unlike YouTube, you cannot upload a custom thumbnail for your video (as far as I know) but you do have more choices that are automatically generated. Here are the basic steps for changing a thumbnail on your Facebook videos:
1. Upload your video.
2. Once your video has been processed go to the “Vidoes” section of your Facebook page.
3. Hover over the video and then click the little edit icon.
4. Along with descriptive information about your video you’ll be presented with a carousel of thumbnails.
5. Choose the best one and click “Save”. You’re done.
Hope this helps!