No matter if you have enabled the setting to show full or abbreviated date and time in your Windows 11 system, time format will be displayed in HH:MM:SS AM/PM in the Notification Center, as ...

Doing so makes Windows and apps display content specific to your location. ... In this way, Windows 11’s time and date are synced with Microsoft Network Time Protocol servers.

If Windows 10 is showing the wrong time and date, it's most likely due to a lack of internet connection. Perhaps you're traveling through different time zones or something went wrong with daylight ...

The Time & language tab has three sections: Date & time, Region & language and Speech. In Date & time, you'll see the current date and time displayed at the top of the screen.