Problems to change store URL in Ver. 1.5.1.3

Hi,

I have created web shop in a directory and now wants to launch the page on the real site.

How do I change the URL in the admin portal? I have changed all the addresses in the config.php file but it does not work so well. some images disappear among others. Talked to my supplier Loopia who mentioned that I also need to change the URL in the settings. How do I do this?

Grateful for answers if there is someone who has had the same problem.