So, on Linux and Mac machines, I generally have the time set to display seconds. Windows has never had an easy way of doing this. Over the years, I had a few third-party apps which forced the issue, but it looks like Windows 10 has a registry hack which will display seconds. They really do need to make this a user-settable feature.
To get to where you need to be, pop open regedit and head to:
You need to add a DWORD called:
The DWORD value needs to be set to 1, as shown in figure.
Then all you need to do is logout and back in to enjoy a system clock as it should be.