Change track/instrument in Garageband using A500 Pro

Hi !
I am very new to A500 pro, love the features and totally lost in terms of how to use them!
 
I have noticed that in ACT mode the dynamic pads can be used to change tracks (instruments) in Garageband. For example, A1 plays my first instrument, A2 switches to the second and so on. I want to use this feature in play mode, mainly because ACT mode does not let me transpose!
 
So can anyone help me toward the right direction?
 
Thanks heaps!