MPC Key 37. Do I have a defective unit?

I hold track and select Pad 2 to open another track but the instrument doesn't change or give me an option to change it.

I also had some problems just selecting my first sounds. I couldn't hear or change the sounds on channel 1 when I had the sound-browser open, unless I scrolled onto channel 2.

Thanks for any advice you can give me. I am a first time MPC user so I may well be doing something stupid.