Rotate screen 90 degrees on mac os?

Question

Multimonitor

In general, the problem is as follows, there is an external monitor that is connected via hdmi, it must work in portrait mode, i.e. you need to rotate it 90 degrees, I turn it, everything is easy and simple, but the main monitor also rotates with it ... which I absolutely do not need ... ! I don’t know how to be ...
everything I found on the topic
osxdaily.com/2010/12/28/rotate-mac-screen-orientation
and judging by the picture it is rotated exactly as I need ....

Answer 1

Hey!
I did it, but I can’t really describe the process, because it turned out somehow by accident) I poked everything in Settings / Monitors
The only useful thing I can say is that I
clicked the turn on the menu exactly on the one that was displayed on the additional monitor -- and everything worked.