The volume buttons always control volume but the middle button's behavior differs based on whether you have Downcast's "Remote Media Skip" setting enabled.
|Headphones Middle Button Behavior|
|Command||Remote Media Skip Disabled||Remote Media Skip Enabled|
|Single Click||Toggle Play/Pause||Toggle Play/Pause|
|Double Click||Skip to next chapter/episode||Skip ahead by Media-Skip Forward Interval setting|
|Double Click + Hold||Fast Forward||Skip to next episode on release|
|Triple Click||Skip to previous chapter/episode||Skip back by Media-Skip Forward Interval setting|
|Triple Click + Hold||Fast Reverse||Skip to previous episode on release|