If you're already attending a meeting and you'd like to test your Audio and Video (webcam) devices, move the mouse to the bottom-left of the meeting interface and a toolbar will appear. On the toolbar, note the chevron icons next to the Audio (microphone) and Video (webcam) symbols.
Select a chevron next to the device you wish to test. Choose from the available options that appear on the screen to select and configure the device.
If you're not currently attending a meeting but you'd like to test your Audio and Video devices, open the Zoom desktop application. Once you have logged in, click the Settings tool on the top-right of the window, and then choose Audio or Video.