When you share forum topics or forum posts on social media sites like Facebook, the site’s default sharer image will currently be used, which doesn’t work well as representation of specific forum discussions. This plugin will use the first image uploaded as attachment in a topic and set it as as Open Graph image (“og:image”), so social media sites (Facebook, Twitter and more) can use it as thumbnail image to represent the link. The process is fully automatic. There are no settings and no image needs to be picked manually.
This plugin only adds the attachment image to the source code, so Facebook and other social media services can pick it up. There is no guarantee, that the image will be used instantly and that later changes to the forum images will be used by social media services. Facebook caches the images and loads them asynchronously. So when you share an URL for the first time, the image might not show instantly. If you want to test what Facebook is picking up, go to https://developers.facebook.com/tools/debug/sharing/
If you don’t see an image for your topic URL or it is an outdated one, click “Scrape again” until the correct image is loaded.