Starting off with the primary display thing, that is kind of a fucky thing with Nvidia at least (can't remember how it was with AMD). On my 1050Ti I want to say the ports in order from 1 to 3 go DisplayPort, HDMI, and then DVI. So even though my main monitor is in fact DVI, my TV connected to DP ends up being the primary, so if I ever have to muck around before Windows starts I need to use it, which is rather annoying.
Anyways, first stop would be playing around with your TV and checking for anything relating to overscan, PC mode, or game mode. Had a similar-ish issue on my dad's living room TV (an older RCA fwiw) and changing that HDMI ports' name it to game mode fixed the issue.
Another thing that could help (even though it's not ideal) is messing with overscan in the Nvidia Control Panel. I believe this is the right area to do this kind of adjustment in, but I'm not able to check for myself since I don't have this issue obviously.
Fixed the issue; I was messing about in the nvidia control panel looking for overscan and for some reason i decided to drag around the boxes on the display config bit on the set up multiple displays tab, i clicked apply and my monitors did the usual turn off and on thing they do and when they came back on things were as they should be. weird how i did the same thing in the windows settings and it did nothing.