Collection cover photo!

Hi all!

Does someone here know how to change the collections' cover photo?
I do not mean the long narrow cover that you see on the top of the page when you are in one of the collections though. I am referring to the cover you see when you are on your collection page with all of your collection thumbnails, which seems to be the first picture in each collection. I am wondering if that can somehow be chosen manually.

Thank you for any tips!