Hover over the bottom of your Zoom window to reveal the menu

Click "Share Option" in the centre in green

To identify the screen to share:\
\- On the panel, Zoom highlights the selected screen in dark blue (by default, the one in use when you click "Share screen")\
\- The selected screen has a light blue frame \
\- If you have several screens, you will also find a number in the top left of each screen, matching the screen number in the Zoom panel

zoom.com

This guide provides step-by-step instructions on how to screen share on Zoom. It includes tips on how to identify and select the screen you want to share and also mentions advanced sharing options. If you want to learn how to effectively share your screen during a Zoom call, this guide is for you.