The Intel integrated graphics adapter in your computer is most probably
the source of the problem.
The thread Force 4:3 ratio / pillarbox with 540M explains it :
Your "problem" is not a problem at all but its the nature of your
machine. You have an "Optimus" system which means you have an intel
graphics processor and an Nvidia.
You do not have the option in the Nvidia control panel since the intel
driver / graphics processor is the default processor to handle video
scaling. Hence no option in the Nvidia control panel.
In the nvidia control panel you should only have 3D and video options.
The "display" options for which the scaling is located in the nvidia
control panel is not needed since the intel driver handles that part.
So yeah, in a nutshell there's no problem.
Another entry in the same thread says :
Not having experience with Optimus it was just a guess, as it works
that way on my PC with HD4000 and AMD gpu.
When the integrated is selected as default in BIOS the AMD control
panel is not fully functional (Don't have integrated on the Nvidia
machine). I find it more difficult to get good results with the HD4000
re - aspect ratio.
If your BIOS has an option to define the nVidia Geforce as default,
this might fix the problem, but might place more demand on your battery.
The thread Stereoscopic 3D missing in nvidia control panel has a simpler solution,
which is to ensure during the Nvidia driver installation that all its components
are marked for installation, even the ones that are unchecked by default since
they are currently handled by the on-board Intel adapter.
Try to reinstall the Nvidia driver to see if this is also true in your case.
You could also go on the NVIDIA Driver Downloads page and use the automatic detection
mechanism via the "GRAPHICS DRIVERS" button, to see if it suggests the same driver
package that you have already downloaded.
This requires Internet Explorer or having Java installed for other browsers.