I laid my tablet on top of the piano to write something and inadvertently pressed some button or combination of buttons. Now when I press one key at a time, I'm getting all kinds of combinations of notes, chords, or sounds... some really strange. I have no idea what happened and no idea how to fix it. How do I reset the piano back to just "basic" piano- single note sound? Tried reading the manual, but can't find the answer to my problem. Help, please.