Check Date & Time preferences
Choose Apple () menu > System Preferences, then click Date & Time. If the date or time isn't set correctly, make sure that ”Set date and time automatically” is selected and your Mac is connected to the Internet. Your Mac can then get the current date and time from the network time server selected in the adjacent menu.
If you don't have an Internet connection, or you want to set the date and time manually:
- Click in the corner of the window, then enter your administrator password.
- Deselect ”Set date and time automatically.”
- Click today’s date on the calendar, drag the clock’s hands to the correct time, or use the fields above the calendar and clock to enter the date and time. Then click Save.
- Check the Time Zone pane as well. It has a similar checkbox for setting the time zone automatically.
Check Language & Region preferences
Choose Apple () menu > System Preferences, then click Language & Region.
- Make sure that the Region menu is set correctly for your region.
- Use the ”Time format” checkbox to control whether your Mac displays time in the 24-hour format.
For advanced formatting options, click the Advanced button, then check the settings in the Dates pane and Times pane. These settings control how dates and times are displayed in the Finder and apps. If any settings have been changed, you can click the Restore Defaults button in each pane to return to the default settings for your region. If the button is dimmed, your Mac is already using the default settings.