When you or others share your registration page within social networks you want to display your own content. Within the page builder on registration page is where you add that info before any sharing takes place and how to have them display right away and not wait for internet spiders to crawl the sites and take it back to other servers. Links below makes it happen and display right away.
After you add in the social meta data into your EW event and save and publish it copy your registration url from publishing options and go to https://developers.facebook.com/tools/debug/ and paste in that reg url into it and click debug
If it has not been shared on FB before you will click on fetch new information
once it gets the data it may or may not be what you added into EW and it may take some time for the servers to propagate the correct info. You can click on scrape again or re scrape as often as you wish until it displays the correct info
For Twitter you can go and do same thing here https://cards-dev.twitter.com/validator and click on preview card button. if it does not show keep clicking on preview card to re load.. again it may take time but it will force it through eventually
For images and data to appear within linkedin you only need to ensure you have an image and data set up within the Facebook share settings as shown above