Cant change the realmlist

Hello.
I am trying to change the realm list in the config file ( wotlk ) and after changing it i make sure that the file is really changed.
After that i run the game and get the previous realm on.
When i check the realmlist file again i see that its changed back to the previous realm.
Basically i hit on the game folder> properties>uncheck read only>ok ( no error at all) and then i hit properties again and see that read only is checked again.
When im changing the realmilst file it does change and the read only is unchecked on it but after i launch the game its changes back probably since the folder is still read only.
Any help would be appreciated.