MacOS Meetings (not webinar) app: giving screen share ability to participant(s)

I'm unable to give a participant the ability to share their screen when I host a meeting.

I have:

1) followed the instructions found at 2:50 of this video:

https://support.zoom.us/hc/en-us/articles/201362153-How-Do-I-Share-My-Screen-

2) checked my zoom profile » settings » meeting » screen sharing and the option is enabled

(Question: Am I correct in thinking that the settings here are default and can be overridden in the app's screen share button's  » advanced settings options?)

3) toggled every combination found in the app's screen share button's  » advanced settings options area.

Participants are still unable to see the option at the top of their screen showing the host's desktop to change the screen being shared from the host's screen to their screen.

What am I missing?