Ims 20

[Darknight]

Hi guys,
Well first post and i must apologise, i know this is the wrong section, but seemed the better of all the options, please put this somewhere else if you think itl be more appropriate,.
I have the ims 20 for the ipad, and i must say its brilliant with fantastic sound, but im wondering about how or if i can change an instrument on the synth when using it in song mode, but without it influencing the rest of the pattern before it?
Hope i made sence their...
Cheers for any help