No need to run as root.
This tip feels kind of obsolete - but anyway…
When you run
nvidia-settings to create your X configuration - no need to use root.
Just run the application using the menu launcher.
When you have adjusted your settings select the Save to X Configuration File from the tab X Server Display Configuration and when prompted for a file name - use your home e.g.
Depending on your use case you will either copy the file to
/etc/X11/xorg.conf.d/20-nvidia.conf or you may want to replace the mhwd generated file in
$ sudo cp nvidia-xorg.conf /etc/X11/xorg.conf.d/20-nvidia.conf