Social sharing returns wrong image

Hello,
nice theme, really good looking and straightforward.

The only problem I have is with my social sharing. When I try to share one of my articles, on facebook for example, I don’t get the right image for the thumbnail. It gives me more than often the image from other articles that are not even displayed in “you might also like” and in my sidebars (no where to be seen on the page I’m sharing).

How can resolve this problem?

Thank you for the attention