I think @Tristan is referring to the keyboard at the top of the screen.
Just to clarify if you click on a note on the keyboard all you are doing is adding a note to the chord. If you want to transpose the chord up or down the keyboard (i.e. change the pitch) you need to use the transpose buttons that are positioned below the keyboard (see Introduction to the CHORD page, The Chord Page: Inversions, and The Chord Page: Entering Custom Chords in the Tutorials category.