Configuring Date and Date/Time field formats
Platform uses the date and date-time formats you specify on the My Localization Settings to format Date and Date/Time fields. On that page, you specify both a regular format and a long format for date and date/time. You can control whether Platform uses the regular format or the long format when creating or editing a Date or Date/Time field. Select the property Display full text date value rather than abbreviation to use the long date or date/time format. Deselect the property to use the regular date or date/time format.