I'm using my 4k monitor which is an LG. However, my graphics card does not recognise that's it's an LG so I can't convert this resolution to 4k. Idk why
have you tryed to restart the pc cause sometimes the pc dosnt update when you swap monitors with the system live and running i had to do that with my pc this moning when i hooked up my secound monitor while the system was up and runing it didnt update