Mac how to use the second monitor if the first (second) is running a full screen application?

Question

macOS

Hello. Such a problem. I have a second monitor connected to my macbook pro, and if I run an application, a game in full screen mode on the same video, the second one becomes inactive and displays a black background. How can I run the application in full screen on one of the monitors, and at the same time use the second as usual?
macOS mojave MacBook Pro (15-inch, 2017)

Answer 1

this is not a glitch, and no need to reinstall the system.
System Preferences -> Mission Control -> Displays have separate Spaces

Answer 2

You have some kind of glitch, I can run something on the monitor in fullscreen without any problems, while the second one does not turn black.

Answer 3

either reinstall mac os from scratch without restoring from a backup (at least test, backup the system, roll from scratch and see how the monitor behaves in this case), or try another monitor on the current version of the system.
A lot of monitors passed through my hands, I used up to 3x (including a macbook) in my work, I never met such problems with either games or videos ...