Go to windows settings.
Select ease of access.
Select color filters. 
Select related color settings on right side of screen. Scroll down.
Select Dark. 
Exit out. 
Maybe I am not being clear the DARK mode which I have already tries relates to changing the 
ENTIRE screen to a dark mode white text......including tool bars etc, etc, 
.....that is NOT what I am after.....
I want all elements to remain the same 
.....I only want to change a FOLDER when opened to a 
BLACK back ground with Bold White text same as I have on my WIN7 units..
thanx for trying but no cigar so far..
UPDATE: This little FREE program is very useful 
and I have easily changed TEXT size, Bold, Type, etc..
now to figure out folder background color.
Most Users are using a great small free utility called Winaero Tweaker, 
which will let you adjust font sizes anywhere in Windows 10.
To adjust the font and font size in File Explorer:
Open Winaero Tweaker
On the left click Icons in the Advanced Appearance Settings Section
Then click 'Change Font'
Set your Font Size . . . etc.
Click Apply Changes
Then either log out or restart your PC for the change(s) 
to take effect
Click the link below to get WInaero Tweaker:
https://www.techspot.com/downloads/6911-winaero...