>>> "I was informed that Microsoft was changing the background colour from white to black"
The background colour of WHAT, exactly? The background colour of the web page you're viewing now, for example, is determined by The Answerbank's web designers and has absolutely nothing to do with Microsoft. Similarly, the background colour you see when typing a document in, say, LibreOffice Writer or OpenOffice Writer, is determined by the software that you're using and, once again, has nothing at all to do with Microsoft.
Some Microsoft programs, such as Word or Outlook, do offer a so-called 'dark mode' (with a black background) but it's an option and definitely not something that you're forced to use.
So, unless you explain further, I've absolutely no idea what it is that you're referring to (and I very much doubt that anyone else here will have either!)