A cover is the picture the calendar and the grid preview show for a reel. You can choose one once the post has one video on it.
- Open the post and press the Media tab.
- Under the video, beside Cover, press Choose a frame or Upload your own. On a phone, press Change.
- For a frame, drag along the reel. The dashed band is the part the profile grid shows. Press Use this frame.
- For your own, press Choose an image. A JPG or PNG at 1080 by 1920 fits a reel exactly. Press Use this image.
Once the post has gone up, Instagram's own thumbnail is shown instead.