casio: stored numbers keep changing!? (1 Viewer)

[Exp]

My casio fx-82AU Plus calculator's stored numbers keep changing somehow and I don't know why...
Letters A-D are all fine but when I store numbers into X,Y,M and come back a bit later, the numbers change!

How can I fix this/ what am I doing wrong?

 

[BLIT2014]

Maybe try doing a hard reset back to original settings?

 

[BLIT2014]

Or take the battery out then back in again (or replace the battery).