The favicon appears usually in the favorites menu (bookmarks in some browsers) of a browser. Your favorite icon (commonly referred to as the favicon) is an image file that is 16×16 pixels, and is normally named favicon.ico.

For Example: Change Favicon image in SJ Tekmag Template
 

 
To Login Administrator Panel

To change favicon image of Joomla Template, please go to Administrator Panel >> Extensions >> Template Manager

 
Next, you need to hit “sj_tekmag – English”

 
Next, you need to click “General tab” >> Find “Favicon” in “Global” parameter

 
Next, you need to click “Upload”, You can even upload an image straight from your documents, then click “Insert”.

 
Finally, hit the “Save” button, and you should have your new favicon.

NOTE: Since your browser has already downloaded (cached) your old favicon, you probably won’t see the changed icon till you clear your cache and refresh (you may have to refresh multiple times before you see the changed icon).