If you would like to show a different image at the top of the specific content page from the one that shows in lists of comments, you may add an alternate hero image here. This will turn the "Main Image" field into an image just used for lists of content (for the teaser and social media). This image should be a minimum of 800 pixels wide, and will look better if it is fairly short (so, has more of a thin landscape orientation rather than a tall vertical one).