Boss JamStation JS-5 Owner's Manual page 24

Let's Try Playing Some Sounds
Listening with a Different Chord Progression
The Preset Songs feature one additional Chord Progression. Let's try
playing a Preset Song after switching to this Chord Progression.
fig.QS02-12
1
While play is stopped, hold down [SHIFT] and press [EZ],
getting the button to light.
2
When [START] is pressed, the performance begins with
different chord progression.
3
To return to the original Chord Progression, hold down
[SHIFT] and press [EZ] while play is stopped, extinguishing
the button's light.
* You cannot switch the Chord Progression if [SHIFT] + [EZ] is pressed while a song
is playing.
24
1,3 2