[solved] Qubes 4.2.2 not detecting external monitor - Nvidia RTX 4070

I read the topic and did: add new qube ‘sys-gui’ then in change mode to HVM and then in device tab added Nvidia to list
when I run sys-gui, it ask to login to system again then the external monitor goes off. what is my mistake?

There’s no chance to use external monitor in Discrete mode

Would you please explain more or give me a topic to understand, because I’m not a tech guy.