Set the date and time automatically on your Mac
You can have the date and time set automatically using a network time server. Be sure your time is correct so time stamps on emails, messages, and files are correct.
On your Mac, choose Apple menu > System Settings, click General in the sidebar, then click Date & Time on the right. (You may need to scroll down.)
Turn on “Set time and date automatically,” click Set, then enter a network time server for your region.
Turn on “Set time zone automatically using your current location.”
To choose the formats used to show dates and times in other languages on your Mac, see Change how dates, times, and more appear.
Tip: Click the date and time in the menu bar to open Notification Center. See Use Notification Center.