Clean the gold contact points on the earbuds and inside the case with a dry cotton swab. Sometimes sweat or dust creates a barrier. Sound is too quiet:
Audio and Call Controls: Pause/Play: Double-click the MFB. Previous Song: Long-press the L side MFB for 1 second. Next Song: Long- YYK-Q80 Clip-on Bluetooth Headset User Manual yyk-q80 user manual
Here are the key specifications of the YYk-Q80: Clean the gold contact points on the earbuds