The sound output level from the AV terminal is interlock with the built-in speakers. If the initial setting of the output to the speakers is low, the audio output from the AV terminal is therefore low as well.
Please refer to the steps below and the user manual of respective product to check the volume settings for both the computer and the device.
1. Set the volume output of the device to Minimum.
2. Connect both the devices using the recommended cable. Use of unqualified cable can cause damage to both devices.
3. Increase the volume output of the computer to Maximum.
4. Slowly increase the volume of the device to the desired level.