Get it

Quad shortcuts

1 – 6Box fills the tab and gets the sound. The same key again goes back.
⌥1 – ⌥6Sound from that box only. ⌥0 mutes everything.
S / ⇧SMove the sound to the next or previous box.
GPick games.
PKeep the control panel up (or touch the bottom edge of the tab).
BHide or show the box toolbars.
?Show this guide again.
⌃⌘FChrome full screen, or the Full screen button in the panel.

The keys work inside a box too, except while you're typing. Drag a box by its toolbar onto another box to swap the two (with toolbars hidden, drag its little number). Clicking a player's own speaker icon gives that box the sound.