Leezone,
If I may give some advice :
a. Tell the Audya owners what voice you start with.
b. Also tell them what part of the keyboard your are talking about (left or right)
c. Tell them what voice you switch to.

A little explaination :
FX is NOT a basic part of a voice, but is added 'afterwards' and has not a direct relation to the key-trigger. Therefore in many/the most instruments FX's do change immediately as a new voice is selected.

All these problems can be avoided with sufficient seperate FX-es onboard. For example :
try to program FX1 for voice #1 and FX2 for the next voice you choose...

Sure, nobody likes this behaviour but as Niels stated most kb's do have this 'feature'.

Method #2 to avoid it : Release the (right-hand) keys while changing voices.

And.... please relax