Hi In Thunderbird - 3 bar menu - Preferences - Calendar, you will find settings for how reminders are set. Hope that helps, Agnes

Abbreviated responses leave many less technically oriented users clueless. What is the "3 bar menu"?

Thee bar is actually the easy description, also known as the "hamburger" or "hotdog" menu. In fact it is simply the usual icon for any menu. Look for 3 horizontal bars on your screen. You placed this as an answer on a previous question, which means only the original client and I would see it. If you need help please start a new question so the experts will see you need help.