How to use audio and subtitle keys in android app "WDTV MediaPlayers Remote"?

I’m using the “WDTV MediaPlayers Remote” app on my Samsung galaxy S2 i.c.w. WDTV live hub.

It’s a great app but i just can’t figure out how to use the “shifted” buttons of the four colored keys (B,A,C,D) and (subtitle, mute, audio, prevpage, setup, nextpage).

Ok, but why ask here? This app is made by WD?