That's where the "Linux is not Windows" phrase comes into play.
You'll get used to it. I used to feel that way too but I've since seen the wisdom in the way Linux works.
I am not trying to be rude here but this comment is SO refreshing to see! There are unfortunate assumptions that seem to come with many people who have used Windows for a long time, that solutions are about using "superuser" powers to bludgeon the system to your will. Linux was designed from day one as a true multitasking, multiuser operating system. You should always look first for a solution that solves the problem for the individual user with NO effect on other users.
For example, I have one system that I maintain that has 5 users each with very different needs in terms of the Monitor they sit at to access the same X server; ranging from wide screen laptops the new LCD to old CRT monitors. What happens if I charge in as "superuser" and save the nvidia-settings for my monitor to the /etc/X11/xorg.conf file and the next poor user tries to login using a totally different configuration? Trouble is what.
The reason the nvidia-settings tool does not ask you to automatically become the "superuser" is because it can be used by individual users to suit themselves.
Run the tool, setup what you want - this creates a config file in your home folder called .nvidia-settings-rc. To start that file automatically when you (AND YOU ALONE) logon you create another file in your Home folder called .xinitrc - notice the dot as it is another hidden file. In that file put this text:
/usr/bin/nvidia-settings --load-config-only &
Save the file and make it executable -
$chmod +x ~/.xinitrc
Then make a soft link from .xsession to .xinitrc -
$ln -s .xsession .xinitrc
When you log on these files are read by the X server - load the nvidia-settings config for YOU without actually running the nvidia-settings program, then continue to load your session (I use Gnome version of Mint).
Do this for each user on your system and the individual settings can be as different as you like.
Linux is more complex because it is more powerful. Don't "club" it to get what you need, learn it and work with it - knowledge is power!!