Android P

Android P will automatically remember Bluetooth A2DP device volume levels

Android doesn’t currently remember Bluetooth volume settings on a per-device basis, which is a bummer. If you leave volume on loudest while streaming to a wireless speaker and then connect your earphones, they’ll also blast at full volume. That’s not a good thing and Android P will apparently introduce a fix.

According to a new Android Gerrit, first spotted by the folks over at XDA, Android P will be able to remember different Bluetooth volume settings for each device you connect to your phone. This feature is expected to roll out in Android P Developer Preview 2 and be ready for prime time in the final release.
With the update, Android will start storing the last volume used on each device in a preference file and will be to automatically apply the correct volume setting the next time you connect that particular device. This feature has been a part of iOS for some time and is sure to be appreciated by Android users who stream audio to Bluetooth devices on the regular.
Speaking of volume settings, Android P will also shift from the current horizontal volume slider, to a vertical one with a mute button below. This one is more of a cosmetic change, though the vertical orientation does seem more intuitive, seeing as how volume rockers are always on the side.