There are two ways to create Highlights and add covers.
1st. You can also save old Stories as Highlights:
1. Go to your profile and tap below 'Stories Highlights'.
2. Tap to select the Story (or Stories) you want to add to highlights, then tap 'Next'.
3. Choose a cover photo and enter a Story name for your highlight, then tap 'Add'.
You can add more photos or videos to your highlight at any time by tapping 'Edit Highlight'.