Set the date and time on your Mac
You can have the date and time set automatically using a network time server, or set your computer’s date and time manually. Be sure your time is correct so time stamps on emails, messages, and files are correct.
On your Mac, choose Apple menu > System Preferences, then click Date & Time.
If the lock at the bottom left is locked , click it to unlock the preference pane.
Click Date & Time, then set the date and time automatically or manually.
Automatically: Select “Set date and time automatically,” then choose the network time server for your region.
Manually: Deselect “Set date and time automatically,” click today’s date on the calendar, drag the clock’s hands to show the correct time (or enter the time), then click Save.
Click Time Zone, then set the time zone automatically or manually.
Automatically: Select “Set time zone automatically using current location.”
Manually: Deselect “Set time zone automatically using current location,” click a location on the map, click the Closest City pop-up menu, then choose the city closest to your location.
To choose the formats used to show dates and times in other languages on your Mac, see Change how dates, times, and more display on Mac.
You can set options to customize how the time and the date appear in the menu bar. See Change Dock & Menu Bar preferences.
Tip: Click the date and time in the menu bar to open Notification Center. See Use Notification Center.