Announcement authors can supply a cover image for an Announcement; this image is then displayed on the Announcement Card across the whole application.
Cover Images are only available on Announcements.
When creating an Announcement just select the Cover Image option.
Add an image file. Please note that this image must be uploaded separately to any other images you have included or attached to the announcement (but it can be the same image if you like).
You may also like to Pin your Announcement. More information on pinning Announcements can be seen here.