DIAGNOSIS You're not missing a setting; the 2x 2W internal speakers are a basic convenience feature. They lack bass and power by design, intended for system sounds, not media.
FIX Maximize what you have, then plan for external audio.
- Press the volume up button on the remote or use the OSD (System > Volume). Ensure it's at 100.
- In the OSD, go to Sound > Treble and lower it to around 2 or 3 to reduce tinniness. You can slightly boost Bass, but it will be minimal.
- On your source device (PC, game console), ensure its system volume is maxed.
- For any real audio quality, connect external speakers or headphones. Use the monitor's 3.5mm audio-out jack or connect speakers directly to your source device.
IF THAT DIDN'T WORK Check your source's audio output settings. On a PC, right-click the sound icon, select Sounds > Playback, right-click the BenQ device, select Properties > Levels, and ensure it's not muted or low.
HEADS UP When using the USB-C connection from a laptop, the monitor becomes the default audio device. If you plug external speakers into your laptop's jack, you may get no sound unless you manually switch the audio output back to your laptop in the OS.