A friend of mine uses Thunderbird. The background colour behind his inbox list of emails has changed to black and the email subjects lines have changed to white text - so thats still readable although black text on a white background is preferred. When clicking on a number of email options however, the text has changed colour to white on a white background making the list of options unreadable. Distribution groups in the address book have also changed to white text on white background. My friend is running a Win 10 machine. Any ideas anyone ?