Finally Microsoft gave Windows 11 the capability again to show seconds on the system clock again.

Microsoft removed the seconds from the clock on Windows 11 as some performance measurement - and in most cases you actually don't need the seconds really. Unless you are sometimes doing stuff like seeking for specific events in logs and want to correlate them to the very moment in time.

If you are interested in why it's removed: Optimization. More details here: https://devblogs.microsoft.com/oldnewthing/20220411-00/?p=106456

Give me back the seconds

Having applied the May 2023 Windows 11 update you can enable the seconds back on the system clock.

Create a DWORD entry with value 1 and name ShowSecondsInSystemClock on this key: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced

Or easier in powershell:

New-ItemProperty -Path HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced -Name ShowSecondsInSystemClock -Value 1 -PropertyType DWORD

In case you want to disable it again, use this:

Remove-ItemProperty -Path HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced -Name ShowSecondsInSystemClock

That's it - really easy :-)