Here its my mod.. To change logo web.. So if you want to change just upload images and select on panel.. You can up more images..
First open your head
Change the logo url with this:
<img src="'.$config['homeurl'].'/images/logo/'.$config['logourl'].'">Open dir images create one dir with name "logo"
Donwload my file so you can see 2 file.. logo.php and sql
Import sql to your db
Import logo.php to admin/includes
Open your index.php on admin/ add my code to access logo.php
So you can up more logo and select anywhere without login to root..
Thanks