Whoops! I can't believe this! Talk about feeling like a complete idiot! I mean I was 1000% positive that I had the resolution set at 4K for those first few days. I went back and forth on a lot of settings though when I first got the game because I was seemingly locked at 30 FPS no matter what resoltion or graphical preset I used. It turned out to be an issue with a setting in my GPU control panel that needed changing. As far as being in 1080P instead of 4K like I thought, the only thing I can figure is I changed it to 4K when I was trying to get the original 30 FPS issue worked out but forgot to apply the setting. Or maybe I did apply it and it just didn't take? Seems unlikely. Or maybe it changed itself somehow? Nah, I'm probably just getting a little senile in my advancing age! I don't know.
I am actually perfectly satisfied with 60FPS at 1080P though, I was just afraid there was a problem with my new PC. So I guess I'll just chalk this up as lesson learned and move on. Thanks for the help q123 and Fox! I really appreciate it!