The cover photo is the image that shows up on your dashboard, and it's also the image that will be pulled in on social media should you choose to share your board there.
The first photo uploaded to a board will become the cover photo by default. To change the cover photo follow these steps:
1. Click on the 3 dots / ellipses on the bottom left of the post you want to make the cover image.
2. Select "Make Cover Image"
Please note - the cover photo must be an image on your board.