Under Background, select Solid color. Then, choose a light background, e.g., orange, and the font will turn from white to black. Then, immediately change your desktop background back to Picture ...

If you do not like the current background of your Outlook calendar, you can always change the color to a different color. You can also make your calendar distinctive, especially if you are working ...

Some of the preset themes change the color of the background, tabs, and toolbar. Uploading your own image is also an option, ...