Hi.
The "short term" memory (80 minutes) use a little battery to work.
Lifetime for the battery are most often 5 years or so, the same as i.e.in a PC mainboard to
backup Bios etc.
A replacement should fix that easiy, but to save your settings on a floppydisk or whatever
media the different keyboards use, are always a good idea.
I also you'll find something about this matters in the usermanual.
Happy Playing
GJ