WHY DOES MY VIVOACTIVE 4S CONTINUE TO MISREAD ELEVATION EVEN AFTER A FACTORY RESET

My Vivoactive 4sis misreading my elevation daily, I have reset it and this has not changed.  i have completed a factory reset 3 times in the last year because of battery length, misreading heart rate, and now because it is counting too much elevation. I normally average 3-4 flights of stairs daily, and it is reading 20+ flights.