All menu settings are located to wp-admin>THEME NAME> menu options. 
We can change the text color into the "Main item Typography" settings.

If we want, we can apply a background color to the menu container. 
Another background color option is available for the mini menu.

Those settings are applied by default on the whole website, but we can overwrite the menu text color and the menu background color on a specific page in its page settings.
If you have imported a demo content and you dont understand why the menu text color from the "menu options" doesnt seem to work, this is probably the reason. Please take a look in the page settings.