When you share on facebook, twitter and google plus, depending on what’s inside the html code, data is extracted, which is then compressed and used for the share window: description, image. Especially for the latest typology of data, sometimes sharing on facebook without careful care may result in the use of an image not exactly the same as that you thought.
For example, if you’ve included a logo for the entire site, and maybe in the articles you’d like to publish the featured image, or the attached one, you might have experienced the problem of sharing a post with the logo of your website and not knowing how to avoid this problem .
A plugin that can help us in managing this data, also called Open Graph, is Facebook Open Graph, Google+ and Twitter Card Tags. The following Free Plugin will give you a hand in customizing this information so that each time you share, you will always find the correct pictures you want.
These customizations are also available for other social networks like twitter and google plus, so you can always get back to it. In the case of facebook I remember you need to use the Facebook debugging tool to see how a link is shared on the social network.