On your laptop at the windows desktop.
Next to the time you will see a speaker icon.
Right click on it, and from the pull down menu that appears select playback devices.
In the main box you will see a list of playback devices.
Right click on HD audio, or speakers.
Click on set as default playback device.
If you have a reference to HDMI audio also.
By right clicking on any and selecting set as default playback device the audio will switch from the laptop speakers to the Hdmi cable connected to the projector.
This how you switch audio playback to different devices in windows Natsavali ok .