Hello there Firefox553 We have read your message We try to help you. Sometimes it changes by newer versions with windows use. Also by Thunderbird. You’ve can change it in the menu or use newer themes. https://support.mozilla.org/en-US/kb/install-themes-change-look-thunderbird Read this please http://kb.mozillazine.org/Local_Folders#Local_Folders_lost_during_an_upgrade Use this for colors in Thunderbird. https://addons.thunderbird.net/en-US/thunderbird/addon/account-colors/ It works with Thunderbird 68.0 https://www.mozilla.org/en-US/firefox/all/#product-desktop-release https://support.mozilla.org/en-US/kb/calendar-updates-issues-thunderbird Greetings Firefox Volunteer.