After you bind skin using interactive bind, you can adjust the volume manipulators interactively in the viewport, or by adjusting the parameters in the Channel Box or Attribute Editor.
To view and select interactive bind manipulators
in the Maya Tool Box.)
A volume manipulator appears around the influence in the viewport. By default, volume manipulators display on one active influence at a time, but you can set other Display options.
For example, to have the manipulators display even when their associated joint is not selected, set the Display option to All. When this option is on, all inactive manipulators display as wireframes, and you can use the pickwalk hotkeys to move between manipulators.
To adjust interactive bind manipulators
To adjust manipulators in the viewport, drag and 
-drag the manipulator edges to change its shape and size. You can also use the manipulator translate and rotate controls to
adjust its position.
The following table summarizes the ways you can manipulate volumes. (These descriptions assume the default capsule volume type.)
The region you affect highlights in yellow as you manipulate it.
The images above do not show the manipulator rotate and move controls. To shrink the rotation rings and move arrows in your scene, use the + and - hotkeys.
As you adjust the manipulator to include or exclude vertices, Maya updates the weight color feedback for the associated influence in real time.
You can adjust the Falloff curve or select a different color ramp preset in the Skin Binding Settings of the Interactive Skin Binding Tool.
