OK, you seem to be confused: The defaults directory is not your current settings, it is the 'template' for settings files that will be created for each user of your computer the first time they run mIRC.
Your personal settings are located within your own user directory, at <DRIVE>:\Documents and Settings\<USERNAME>\Application Data\mIRC (on XP), <DRIVE>:\Users\<USERNAME>\AppData\mIRC (on Vista), and something slightly different on earlier versions of Windows. The Application Data/AppData directory is hidden (by Windows, not mIRC), so the easiest way to get to the folder is to open mIRC and type //run $mircdir