If you want to achieve more noticeable, clickable and shareable content on your social media page and on other peoples pages when they link to one of your posts, you really need to use Open Graph images.
IPS4 includes support for these, but it's not optimal.
Fortunately there's an amazing tool in the IPS4 available, which allows your staff members to choose any image within a topic as the one, which is going to be used for the
https://invisioncommunity.com/files/file/8838-embed-enhancements-ii/
Edit:
There's now also another application available which supports this:
My own IPS SEO Essentials Application which helps people to optimize their Invision Community Suite.