As height, gender and age are all parameters within the scan process they are all set to each reading. This basically means that all that information is used in the algorithm to calculate some metrics within your reading.
Changing any of your core parameters does not change the results from your previous scans.
We recommend deleting the incorrect readings (If you have entered any of the pre-scan questions incorrectly) as this can hold a baring on the final result and you may see some metrics change upon subsequent scans. You can find how to delete readings within the FAQ too.