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A chord can obviously be played in numerous ways. ProChords does not cover all combinations, but with the tweak buttons you will get pretty far.

The bass buttons:
If you take a look at the piano on top of the screen while you press the bass buttons.
+ and – will move the bass note. You will see that the symbol on the piano above appears either in blue or red. Blue indicates that the note is part of the chord you have chosen. Red is for notes that are not part of the chosen chord. If you prefer no bass note at all, just press – till the note disappears en the left side of the piano.

The octave buttons:

Let’s say you have a C chord in your progression band and want to go down to a B chord. ProChords will suggest a chord upwards almost an octave higher.
Then press the -1 button, And the chord will be placed an octave lower.
The octave buttons affects all the chord suggestions you are about to add.

The inversion buttons:
If you press either the + button or – button the chord will roll up or down on the piano. (Until further development of ProChords, chords containing a 9, 11 or 13 can’t be inverted).

Read: How to find or modify a chord using the chord wheel or Download ProChords for your iPhone