There are several types of variables. LNG variables are language variables and are set up in the language.ini files in the /language/[your language]/ folder.
Most of the default language variables are in the front_language.ini file, but if you don't find it in there, it will be in one of the other ones.
Be careful which editor you edit the file with. Try to use Notepad unless you have an HTML editor. Microsoft Word can sometimes damage an .ini file by adding Microsoft machine code to it. Just be sure to save off a backup of the file you're about to edit just in case.
