Ahh the Windows Login screen... sometimes you see a picture - you wonder where it is - but you press the mouse or your finger is resting by the finger print reader and darn it! you have a login prompt.
This blurs the picture and makes it impossible to see where it was taken (hover your mouse near the camera icon "like what you see?" or click one of the other search "bait" links "wonder what the fuss is about?" you know the ones...
It turns out it's simple - just log in, and then hit the combination for the lock screen Windows + L
You will be returned to the lock screen before the picture changes to the next one!
It turns out there are a LOT of those shortcuts, but you can find a complete list on the Microsoft site here: https://support.microsoft.com/en-ca/help/12445 under the category "Windows logo key keyboard shortcuts".
Learning some of those shortcuts might help you work faster if you switch programs frequently - it's probalby worth taking a look at and trying out some of the functions to see what they can do for you!