Does not use Featured Image! Why???

I’m wondering why when I share a post to facebook the plugin is pulling images from my sidebars? Why is it not using the Featured Image (post thumbnails)? Isn’t that what the post thumbnail is for?

https://blog.avantagency.com/fashiontv-video/

I flip through the thumbnail options but never included in the Featured Image.

So every time I share to facebook, no matter the Post, it always uses the same image.

I hope there’s a fix.

https://www.ads-software.com/plugins/simple-share-buttons-adder/