If you activated the Animated thumbnail option, you will need to deactivate it.
Yet, we recommend using animated thumbnail, as it makes your Stories and Carousel more visible.
Steps to follow
1. Pick the widget of your choice, and click Edit
2. Open the video listing
If widget is "Bulk" 👇
If widget is "Regular" 👇
3. Pick the video of your choice
4. Upload an image, and click "Done"
🎉 That's it! You know how to change video thumbnails with custom images.