How do change the zoom webinar recording size to only record the active Chrome window?

[dunrented]

I have an extra wide monitor at 3840x1080. When I start the webinar, the recording is made with the full width of the screen. However, what I share to my audience is a single Chrome window at 1920x1080. How do I force Zoom Webinar to only record that screen or that portion of my monitor?