Favicon is an icon that appears next to your store name, browser tab or address bar.
It will also appear under the Favorites tab.
1. Prepare a 16×16 or 32×32 pixel PNG file and make sure you name it favicon.png.
2. Go to Layout > Click on the three dots > Click on HTML editor.
3. Go to the section Assets.
4. Click on Add a file at the bottom of the list and upload your file prepared in step one.