Capturing a specific window in my second screen

[Goustaf]

Hello, i have my PC monitor and py TV monitor, My PC monitor is my main screen.
I want to play in my main screen, record a stream from my second screen. i have done this:

But as soon as y switch to another window in my second screen, OBS capture both and i dont understand why:

what am I doing wrong? Can you help me?
Thank a lot