I am very fresh with Manjaro. Just installed it!
I have dual monitor setup. From display configuration I set up my DELL monitor to be primary, and my BENQ secondary. However, everytime I reboot/boot the system my login screen shows by default on my secondary monitor. While being on Ubuntu (Gnome) I was copying monitors.xml to the gdm folder and everything was fine. Now I don’t know what to do. Using Manjaro KDE 20.1
Have you tried switching the HDMI ports?
Your /etc/X11/mhwd.d/nvidia.conf has defaulted probably to BENQ monitor, so SDDM will initialize it first. Create a fixed layout or change the Monitor. Might have to change the
"nvidiaXineramaInfoOrder" and the
"metamodes" too, to match what you set on Display Settings in KDE Plasma.
I am sorry for my ignorance, but can you please elaborate a little bit more what should I do?