OnePlus
Change Media Volume for Apps, Games and Videos auf OnePlus
OnePlus phones running Android and OxygenOS separate audio into distinct channels: ringtone, notification, alarm and media. The media channel covers every app that plays sound content, from games and video players to streaming apps like YouTube or Netflix. Voice messages you receive or play back in WhatsApp are also routed through this channel, not through the ringtone volume.
This separation means raising your ringtone volume in Quick Settings has no effect on how loud a video or game sounds. To change the actual media level, you either use the dedicated slider in the sound settings or adjust volume with the hardware buttons while media is already playing, since OxygenOS then recognizes the buttons as controlling media volume.
Open Settings ➔ Sounds & vibration, then swipe left or right on the media volume slider to set the level you want.
If sound is still too quiet or too loud afterwards, check the volume inside the specific app, since some streaming services and games apply their own internal level on top of the system setting. If media sound seems muted entirely, check whether a Do Not Disturb or focus mode is limiting audio, although these modes usually affect notifications rather than media playback.