I have upgraded my Thunderbird to 78.4.0 (32-bit) using Windows 10. I find that the default background colour is not retained after I set it. Under Tools>Options.>Composition.HTML Style the background colour cannot be changed unless I uncheck the option Use reader's default colors. I changed the default colour to white but the background remains black. I want all background colours to be white in all Thunderbird and Firefox windows unless their original colour is nonwhite. Please tell me how to do this. Thank you spruce18b