When I have CSM enabled in bios my motherboard isn't able to find my main drive to boot from

So my main drive has the GPT standard and my bios mode is set to the UEFI, but i can't and dont know how to set the secure boot mode even if it is enabled on my bios. So since I got a new monitor I started to get the error message from the bios telling me to select the correct boot drive. Once i would restart i would go to the bios to to change the setting and notice that windows would only boot with CSM disabled for some reason. Plus for some reason if i try to switch the cables from the monitors the problem reoccurs. So pls if anyone has any tips I would be more than happy yo listen!