Menu Bar Icon is Missing or Can't Change Preferences

If you unchecked "Show NumLock in menu bar", the # icon to display the NumLock preferences window will not be visible.

When the menu bar icon is hidden, you'll need to double-click the NumLock application icon to display the preferences window. NumLock is installed in your Applications folder by default.

If you'd like to keep the menu bar icon visible, check "Show NumLock in menu bar".