To control the image that will show up in your news feed (Facebook and other social media platforms) simply use the Featured Image function.
When creating a new post (Dashboard > Posts > New), scroll down and look for this on the right:
Clicking on Set Featured Image will open up a dialogue prompting you to upload a picture from your computer or choose one from your media library.
Whichever image you upload here will be the one that shows up whenever you share your posts or pages to social media, unless you have the Yoast SEO plugin activated.
In that case, look right below the big box where your main text content goes, and click on the share icon in the Yoast SEO area. This will bring up a place for you to edit your Facebook image, description and title for that particular post or page.
To control the overall image that shows up when you share your blog’s domain name/ homepage (http://www.yourdomainname.com)
You will start by visiting you blog’s dashboard, then click SEO » Dashboard
Next, click on the ‘Features’ tab, then click on ‘Enabled’ under ‘Advanced settings pages’ option and then click on save changes button to store your changes.
Yoast SEO settings page will now reload and you’ll be able to go to Dashboard > SEO > Social.
The first page you’ll land on is where you put your social links, and then when you click on “Facebook,” you’ll find a place to set the homepage image as well as the default one that gets shown when you share a post or page that has no images in it.
If your link still shows the same image after you make the update, then you’ll need to debug your site at the link below:
Just enter your blog URL and hit “Debug” and it will clear out the old and fetch the new information form your site.