From the scan page, you have an option to choose listings as favorites and show only those you marked as favorites. There are two ways to favorite listings:
1. Click the star icon next to the Keepa chart icon on each listing. The star icon should turn green to indicate that it has been added as a favorite.
2. Tick the checkboxes for the listings that you want to add as favorites. Then click the dropdown next to the topmost checkbox then select "Favorite Listings".
To show only your favorite listings, toggle on "Show Favorites" at the top right section of your scan page.
To remove listings from favorites, simply click the star icon again until it toggles to black. Another way to remove favorites is by toggling on "Show Favorites" then use the checkboxes to choose the listings you want to remove from favorites. Then click the dropdown next to the topmost checkbox then select "Unfavorite Listings".