Switch between monitors in a multi-monitor environment
In a multi-monitor environment, the leader or co-presenter can share any one of the monitors at a time. To choose a monitor you want to share, click the Share button in the toolbar and select the desired screen.

When the presenter asks a participant to AppShare, it shares their Desktop by default. If the participant has multiple monitors, then sharing the Desktop will only share their primary monitor. The participant can later choose to share any of the other available monitors by clicking the Share button.