Noisebuddy,
From the manual:
To enter SONG mode, press the [SONG MODE] key.
Songs are created in the SONG EDIT menu, which is accessed by pressing [FUNCTION] + [SONG MODE].
I´m not talking about to enter on SONG EDIT, I´m talking about plain Song MODE.
I accidentally pressed the Song button several times 
I will place a button protection L shaped piece on it.