When a link is shared in Facebook, Facebook will choose an image to show in the post. Â However, the image FB chooses may not be the best one for the purpose.
The Facebook Sharing Debutter at https://developers.facebook.com/tools/debug/ can help you troubleshoot this.
Adding a link <link rel=â€image_src†href=â€preview-image-here.jpg†/> to the page header will define the image you choose here.
Alternatively, there are plugins to handle this for you.
Here are some links to help manage this issue:
- http://www.seosmarty.com/how-to-force-facebook-to-grab-the-best-image-from-your-page/
- https://www.google.ca/#newwindow=1&q=choose+image+to+appear+in+facebook