What is the “Make Favorite” option?
In your collection you can define one set as you favorite set. Just hit the “star” button in the end of the row and it becomes your favorite.
The idea behind this function is to have one primary set with an image which will be used if you share your collection via facebook or twitter or pinterest. Then this favorite set is being used as your cover for the whole collection.
If you don’t define a favorite, the first entry from your collection will be taken.