Hi Zhihan Chew,
To provide an appropriate resolution for this, I need some information on the audio connections. Please provide the below requested information:
1. Have you connected the monitor to the computer using a HDMI cable?
2. Have you connected the monitor using a DVI/VGA cable for video and the 3.5mm audio cable from the output port on the computer to the Audio In port on the monitor?
3. Line Out Source selected in the Audio Settings menu?
Please reply to this message with the requested information and your findings.