I've had good experience with this extension to change the thumbnail to a random frame from the video instead of the grotesque clickbait thumbnails on everything:
https://addons.mozilla.org/en-US/firefox/addon/clickbait-remover-for-youtube/
I've had good experience with this extension to change the thumbnail to a random frame from the video instead of the grotesque clickbait thumbnails on everything:
https://addons.mozilla.org/en-US/firefox/addon/clickbait-remover-for-youtube/