I appreciate that you have included a screenshot of the theme settings as that is very helpful! Could you let us know which theme is being used? This context will help us determine the next steps to adding a favicon to your online store.
If you are unsure about which theme is live on your online store, you can navigate to the Theme Editor and select the three dots that are appearing towards the top left of the page. I took a screenshot from my test store to show you the section I am referring to: