It’s important to make sure your site has a favicon. This is the small image that appears on each tab and helps to brand and identify the site to users when they have many tabs open.
Visit Dashboard → Appearance → Customize → Site Identity, then click on the select site icon button. Select the favicon file that you uploaded earlier. As your favicon should already be square, you can skip cropping.
Click on publish. The favicon should now appear on browser tabs when a page from your website is visited.
If in step 1 above, the customiser does not exist for you, you can arrive at the same place by visiting a URL like this : https://yourdomain.com/wp-admin/customize.php
Obviously change yourdomain.com to be the domain you are working with.