With the change there's a new feature which can be used when creating a new topic - Title Image. The poster can start off the post with an image which is displayed right at the top of the post before any text. In the create topic page you will see Title Image with a couple of options beneath. That can also be done for an exisiting topic if the topic's originator edits their opening post.
Crowdstack now have an agreement with the Unsplasg website to be able to use their huge database of royalty free images. To use this tyoe a search word in the box below Title Image such as penguins. After a moment you will see some images which are faded with Next at the bottom to get to another selection. When you find one you like select it and the image appears (you can change it if you change your mind before posting).
The other way is to click on Upload Image which is to the right of the search word box. You can use this to upload a picture from your device. Note that the recommended size is 1000px wide by 667px tall.