Are you seeing the incorrect date for historical data? If the display was taking readings before you set the time and date, it will save all the historical data taken at that time under the wrong date and time. To correct this, we would recommend clearing your historical data. To clear all historical data you will need to factory reset the display. Press and hold the reset button located inside the battery compartment for 10-12 seconds or until the display completely clears. Once the display clears you can release the button and go through the settings. Verify the date is set correctly right away to prevent any readings from saving in your historical data. Please let us know if you have any other questions. Thank you and have a great day!