Originally Posted by zebra90210
I run my system on HIGH security level so that no one can mess with my files.
At the moment you are running the GUI as root, you don't run your system on high security level anymore. That is, any applcation can do anything, because everything which is executed is executed with root credentials. I don't need to tell you not to log in as root. One day you'll notice.
In addition to what Wim Sturkenboom said, you can start any single application application by pressing ALT-F2 and then press "Advanced" or "Options" and change your credentials.
Last but not least, logging out as user in the GUI, and then log in as administrator to do an administrative task is the Windows way. Very awkward and time consuming. *nux was designed to offer you the best tool to do your work, and hence offer alternative, safer and faster ways to accomplish what you need.