Enable windows 10 dark theme

Here's an easier and faster way to do it. Just: 

 1 - Open search, type Powershell and open it

 2 - copy/paste the following command 

New-ItemProperty -Path HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize -Name AppsUseLightTheme -Value 0

3 - Press enter. Done.
If you want to undo, just copy/paste Remove-ItemProperty -Path

HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Themes\Personalize -Name AppsUseLightTheme