how to change the blogger favicon?

This needs editing your template file.

1. Design the icon and save it as png (ico is preferred, but it's harder to upload). The preferred resolution is 16x16, but i saved mine at 22x22 for greater quality, and it seems it works :) (i think 36x36 is the limit)
2. Upload the icon somewhere (photobucket, pages.google.com), and copy the link
3. Go to Edit HTML under the Template tab in your blog's dashboard
4. Find the follwowing line (Ctrl+f) : data:blog.pagetitle
5. Insert this code below it: link href='URL of your icon file' rel='shortcut icon' type='image/vnd.microsoft.icon' (replace "URL of your icon file" with the link you've copied at step 2)
6. Save the template
In order to see the change, close your page, delete the temporary internet files from your browser and reopen your page