A favicon (short for favorites icon) is an icon associated with a particular website. Favicons display in the address bar to the left of the URL, in bookmarks, and in supported browsers at the top of page tabs.
For the favicon to display on your storefront, you must publish your Website.Your favicon does not display in Preview mode.
For additional information on creating a favicon for your Quick Shopping Cart storefront, see Creating a Favicon.
If you're having difficulty getting your favicon to display, see Why doesn't my new Favicon display?