Solved Using 4K TV but Native Resolution only 1080p?

So I am totally new at gaming. I recently build a rig for video editing but decided to install GTA V because it's been so long since I played anything. My setup is a Ryzen 5 2600x a GTX 1060 3GB, 16GB or DDR4 RAM and a MSI B450M Pro MOBO. My OS is Windows 10 Pro. I am using a 55" 4K TV for my monitor. The only problem is that I can't seem to get the resolution right, I want full 4K but then Windows upscales everything to 300% and it looks comically big on my screen. Also it says my native resolution is 1080, but since I'm using a 4K TV that can't be right. Bottom line is I am confused and I'm not sure what settings I should have to get 4K with everything. Also my GTA V is kind of wigging out on me. I click it, it starts in full screen, but then abruptly exits full screen and seems to go to 1080p, sometimes I can get it back to fullscreen, but sometimes my mouse curser gets stuck in the GTA V window and I have to exit the game 2 or 3 times before I can get it to go full screen. If you have any questions I will definitely try to answer them because I just really want a smooth experience here.
FYI I think I have GTA V resolution set at 1440P.

Bruce said:

I'll tag out of this one guys.
not a gamer and yet to play with 4K anything - simply no need.

but a 55" screen as a monitor sounds awesome.
must be like sitting in front of an IMAX screen!

Click to expand...

lol, yeah I love it, but as you can see it has it's issues. But I think I might have solved it. It seems that I didn't actually have my resolution set to 4k aka 4096x2160, I actually had it set to some weird resolution of 3840x2160. So now that I have it set to proper 4k resolution i'm not having problems with GTA. Although now I have another problem. When watching movies in VLC I can't get the picture to go fullscreen, no matter what I do, Ive tried adjusting the videos aspect ratio but that doesn't work. I've tried setting it to always be fullscreen but that doesn't work either. I always have bars on the side and top of the picture. I'm assuming this is becuase the video isn't 4k but then again when I had it set to that wonky resolution video worked fine. You would think that we wouldn't be having these problems with the prevalence of 4k nowadays. Or I just don't know what i'm doing.

yeah thats what did it. I just reverted back to a older version and it works fine now, weird. Thanks for the help. Very much appreciated as always.

yes sir, thanks for the help.