Below is a step by step guide about how to add a favicon to a Joomla template.
Step 1: Let’s assume you Joomla template doesn’t have a favicon and you are going to add a new one.
First go to your Joomla template folder which is normally located inside your templates folders in Joomla and upload your favicon.
After uploading the favicon you need to update your template_Details.xml file which is also located in the root directory of your template and let it know to include the new file i.e. favicon.ico by adding a new line <filename>favicon.ico</filename> as shown in the screenshot.
After doing so just refresh and you’ll see your new favicon appear in the favicon area of your browser, if it doesn’t appear just hold shift + refresh to clear the cache and download a fresh copy of your new files.
Step 2: Let’s assume you just wanted to update your old favicon.
This one is quite easy and all you have to do is just replace the old one inside your template folder with new one and you are done. Joomla_root_directory->Template_Name->favicon.ico