keynote black screen

Hi community, I have a simple question that I haven't been able to find an answer for so far.

How oh how when working with two monitors in Keynote, do I set Keynote in such a way that it only uses a single monitor? So no black screen, no presenter display. The black screen makes it impossible for me to present on a Zoom call.

I'm hoping I'm missing something very simple here. I'll feel a bit silly, but the problem will have been solved.

Dee.