I changed batteries in my producx scales and they last about two days. This scale has the BMI Age HT etc stuff but we have always only used weight. I have done this at least three times. What am I doing wrong? Original ones lasted years.

SOURCE: Can I reset the scale?

This link allows you to ask questions and request a users manual....I hope this helps. http://www.conair-store.com/cc_contactus.asp

SOURCE: resetting the scale

You do not reset the scale. It only saves the last recorded weight of the user. So, if you weighed yesterday, it will put your recorded weight in memory. The next time you select your user number and step on the scale, it will compute the difference from your previous record and save your current weight.

SOURCE: instruction manual soehnle scale

I have looked and maybe you have the model number wrong the scale you are talking about 63700 Calando Quattrotronic scale is a simple digital scale and does not provide bmi, and hydration.
here is a link to the manual, http://www.leifheitusa.com/manual/63700.pdfit is in several languages including english as the company is european and sells to many countries. If you look english is there it is a very simple manual as the scale is only desinged to weight in either lbs or kgs nothing more. Sorry. If you would like a bmi chart you can get that here http://www.healthdiscovery.net/links/calculators/body_massindex_chart.htm and figure out your bmi based on height and weight in the chart.

SOURCE: SCALE SETTINGS

To change the height/weight/age, hold the user # you want to change it for and the set/save button at the same time for a few seconds.

I am #2, so I hold the 2 button and set/save. Then you can use scroll to change the numbers/options, and set when you have properly set the digit.

First it does height, then age, then gender, then if you want a goal, and then what that goal is.

SOURCE: Fluctuating weight on Digital Scale from one minute to the next..

i believe that, like most electronic scales, the first time you get on the scale you must step off to allow it to zero itself. Then step back on to get your correct weight.