Don't make permanent changes to always open an application as superuser, the root user, because, as others have stated, it defeats the inherent security of Linux.
Instead, where needed, open the application using sudo. It may seem like an extra step, but that is well worth the trouble to avoid having antimalware continuously running in the background, as is needed by another popular operating system.
For example, to run gedit as super, open Terminal and enter sudo gedit. Close that instance of gedit when done. "Editing files as the root user is potentially dangerous, and may break your system in bad ways."
The Dolphin file manager has a built-in check to prevent the unwary from causing harm. That said, I admit to this risky practice (and make disk images to prepare for a disaster I might create). PCManFM is another file manager that does not kvetch when launched sudo... but it may break some functionality. Caveat operator!
As for being unable to make changes to a drive, if it is mounted, some operations are verboten. That would be like trying to change the distributor cap on a car while driving it. First unmount, then modify.