To add favicon for your school, go to:
School Settings - Main settings - Information - BROWSER ICON (Favicon)
1) Download your favicon file by clicking the “Load” button.
or
2) Generate the favicon from the logo by clicking the “Generate from logo” button (the logo must be installed
Remember that favicon must be square. So if your logo is rectangular and you want it to use it for favicon, you need to add white (or any other background color) to the downloadable picture and only then upload the favicon to the platform.