big problem to install my second monitor

[Hensa]

In my Nvidia control panel, advanced option, I have only one choice --> Only use one display ( Single )
I know there should be another choice ( Dual )

I downloaded again Nvidia drivers, but still only one option.
I tried both analog and digital for the 204B driver, I tried all 4 sockets, etc.
Why is it so hard to install ?
I spent about 8 hours today only with that.

Need Help tx

Edit: Believe it or not, I made a random thing 30 seconds after this post and it worked. Of course I tried this thing numerous times in these 8 hours.
Life is strange sometimes ...