If you find your Dates keep changing format in Google Sheets, or they are in mm/dd/yyyy instead of dd/mm/yyyy (or vice versa), you may need to update your Locale settings.
File -> Spreadsheet settings.
- Under "Locale," select "Your Country" (this affects formatting details such as functions and dates)
- Click Save Settings.
- Next, Highlight the entire Date column (in the logbook page) and re-format it as a Date format.
Menu -> Format -> Number -> Date