I may have a solution to your problem with Cortana.
To return Cortana to her natural darker colour, enable the setting "Dark Mode".
To enable this, go to Settings, -> Personalisation -> Colours -> (Scroll Down) -> Dark Mode.
You can disable this setting at any time.
I hope I have helped resolve your problem.
Did this solve your problem?
Sorry this didn't help.
705 people were helped by this reply