Windows 10: Change login screen background color

I upgraded my PC from 8.1 and I had a black background for the login screen before and after I had upgraded it had grandfathered that background color.
Now that I did an in-place upgrade (to fix some bad windows files), it seems it has taken on the default blue since I have accidentally changed themes. I can't seem to find my old theme from 8.1, or change the background color without changing the accent color.
In 8.1 I was able to set a whole wack of colors to different things, including the login screen independently from the accent color but now it seems impossible
So, how do I change the color on the login screen?

:)

 

Lock screen, user login screen

Yes like bossOr said, it is easy to change the lock screen with the time and date. But trying to change the background on the login screen is not obvious, because it is not the same background as the login screen as one would think. Or it doesn't seem
like you can even have a personalized solid color like you could with windows 8.1

 

how I can change the picture?

To change to a solid color login background, make sure you are on the Fall update (10586) of Windows 10. Once you're using that, go to the Settings application. In the Personalization :: Lock Screen section there's a toggle reading something like "Show
Windows logo as background for login screen" - flip that to be off.