Hi Nick,
Refer to the following step and check if you can customize the color of File Explorer.
a. Right click desktop, click personalize,
b. Click **High Contrast #1,**click Color (This option is listed in the bottom of the same Window)
c. Click **Window background,**a new Color Window **** pops up
d. Under the basic colors: select the color that you want to see as the File Explorer.****Also customize the color using the box available on the right hand side of the same Window.
e. After you choose the color, click Add to Custom Colors, click OK.
f. Click **Apply,**click Save Changes.
Note: You may also change the text, Button, Inactive Window colors.
Hope this is useful and do let us know if you need any assistance. We will be glad to help.