Change key from the stage view; set a capo and Unison shows the shapes to play.
In the stage view, change the key from the control bar. Unison re-spells the chords for the target key — pick A♭ and you get `B♭ E♭ F Gm`, never `A# D# E# A#m`.
Set a capo and it shows the shapes you actually finger, while telling you the sounding key.