Wrong Image Shows on Facebook when Sharing Blog Post
Knowing how to make your content and posts from your blog shareable on social networking platforms is important for any business.. This tutorial will cover how to choose the right images and more when sharing blog post links to social networks such as Facebook. Furthermore, we will describe how to use the popular SEO plugin for WordPress “Yoast SEO” to help set the featured image for social networking.
Sometimes though, it happens that the original featured image is too small (smaller than 200x200px) and if there are larger images in the post, often, Facebook will select the larger images.
The first thing you will need to install the Yoast SEO plug-in, which you can find here:
How to Set a Featured Image for Facebook?
When you go to a post, page or gallery, if you scroll down you will see WordPress SEO by Yoast as below:

You will see the various tabs, but as we are specifically looking at setting the details for your social networks, click on Social tab:

Currently we have no image set here, therefore the image that will be used shall be the featured image, or what Facebook deems as the best image for the page. In our case it’s a featured image, which is a placeholder image.

To set the image you want, you can simply upload it to the Facebook image section shown below. Here you also have the option to change the description and title for Facebook.
NOTE! The recommended size for the featured image is 1200 x 630 px.

Once you have added this, update the post, page or gallery and make sure to reset your cache, as sometimes it may take a few minutes to update.
Here is how the updated page looks like, when we share it on Facebook:

Fetch the new Image and Description
If the image and description is not updating, you will have to scrape for some new information. Do this by resetting the Facebook cache. Go to the following Facebook’s debugger tool, add your URL and click on “debug”:
https://developers.facebook.com/tools/debug/

This tool gives an idea about how an URL will be shared on Facebook, what content, which image will be fetched. If you use an already shared URL with this tool then Facebook fetches the latest content, and also updates it cache with the latest content. Click on Fetch new scrape information. If it doesn’t show you the updated image, click on “Scrape Again”. Perform that a few times, until it shows your new image.

Hopefully this will help you now post your posts, galleries and pages with the image that you choose.
Setting a general sharing Image
The last item to cover will be the general social settings, if you want to have a generic image showing when there isn’t one set then you can do the following.
First go to SEO > Social in your WordPress backend:
NOTE if this is not shown, add the following to the end of your site URL: wp-admin/admin.php?page=wpseo_social
If your site is http://johndoe.com/ it will be http://johndoe.com/wp-admin/admin.php?page=wpseo_social

From here you can add all your social URL’s for Google to track.
Next you will want to go to the facebook tab, and in here you will be able to upload a default image for sharing your website on facebook:

Once you have done this, make sure to save your settings, and again remember to scrape the new details on facebook at the link below using Facebook’s debugger:
https://developers.facebook.com/tools/debug/
If you’re still having problems, you can send us a quick message here.