Not the piano roll, the piano editor, in the step sequencer.
I've got this snare sample loaded up, not as an "audio file" or whatever but in the normal sequencer window that shows at start up.
Usually, you hit the little piano in the top right corner and you can change the pitch of individual hits on the active channel, but for this particular sample it just isn't happening.. It's one that I chopped from a break myself but surely that shouldn't matter? It's saved as a wav, fyi..