Dear complete noob ! I have bad news...
Nvidia Surround means multiple monitors running at the SAME resolution, so you can't mix aspect ratios effectively. AMD Eyefinity is one step ahead in this regard as it can theoretically manage different resolutions/ratios/orientations.
You could look for a 1:1 scaling setting in your monitor's OSD to unstretch the picture, but 1) it's not guaranteed to be there and 2) even if it is you would then get huge black bars that kinda defeat the purpose of Surround.
If there is a 3rd-party fix for this very stupid driver-level limitation, I've never heard of it. There's always
SoftTH but it opens up a wholly different kind of multi-mon shenanigans...