Changing img folder address

[Outbackmark]

You would change that in the Style Manager, in the Admin Panel go to
Styles & Templates/Style Manager then select "All Style Options" for the style you wish to update and click "Go"
Now scroll down to the block called Image Paths, this is where you enter the urls to the different image folders, logo etc.
It is often best to use the full url (http://yoursite.com/forums/images), depending on how it is all set up, though you can simply use /forums/images.
Once done scroll down a little more till you see the button to "Save CSS" and click it.