About
When mirroring a Mac device, the default setting mirroring setting may not be correct, causing the projector to not display your screen, or display an erratic screen. To correctly display your device, you must switch the display settings of your Mac device so that it mirrors your device instead. Audio settings must also be correctly set in order to ensure that the audio works as well.
Environment
Mac devices
Steps
To troubleshooting your HDMI connection, select the AirPlay icon at the top menu of your Mac device. From the dropdown menu, select the appropriate device you want to mirror, such as Mirror Built-in Retina Display.
Hint: This option may be different depending on your device so try to select different mirroring options until the issue is fixed.
Next, to present audio from your device, you must also make sure the correct settings are set. To do so, select the Audio icon in the top menu of your Mac device as shown in the image below. This may differ with your device, so be sure try selecting the options there until the issue is fixed. In the following case, TSB48kHz was the correct option.
For more information, please this resource from Apple: Use external monitors with your Mac
For more help, please contact ITS at its@manhattan.edu or 718-862-7973.