If you're connecting to an audio device—such as headphones or speakers—using USB or HDMI, you might need to set that device as the default audio device. If you’re using an external monitor that doesn’t have built-in speakers, make sure that the monitor isn’t already selected as your default output device. if it is, you won’t have any audio. You can check that when you set your default output audio device. Here’s how:
In the search box on the taskbar, type control panel, then select it from the results.
Select Hardware and Sound from the Control Panel, and then select Sound.
On the Playback tab, right-click the listing for your audio device, select Set as Default Device, and then select OK.