Yamaha YPG-235 low volume on piano sounds

by Max
(Shreveport, LA, USA)

Does anyone else notice how low the volume is on the Yamaha YPG-235 piano voices? I went into "Function" and turned up the Grand piano sound as loud as it would go and that helped a little but it reverts to its lower volume every time I turn it off and back on. Is there a way to set these choices in "Function" so that they stay that way?