Suggestion: Volume adjust option in the phone app.

I often play on the phone and when I do, I usually I play bullet games. It's really important for me during bullet games to have a sound when a move is made but there's no option to adjust the volume. The volume is the same regardless of the general volume I have set on my phone. This isn't really a problem for me but the people around me (family, work mates...) sometimes gets annoyed by all the "blips" from my phones. It'd be excellent if a volume option was added to the app!