Problem with typography with widgets

Hi, I’ve just updated to ver. 2.7 today. I am using the Autumn Concepts theme, and have had no problems until now. The theme default shows the archive list, calendar, categories and links in the right-hand column. When I add a widget, it wipes out all of those. So I went ahead and added the widgets for calendar, categories, etc., as well as one for AdSense. Everything is fine, expect that the <h3> tag for category/link headings has now become <h2>, and it’s awful. Where/how can I change those widgets (I assume that’s where the problem is) to have the right tags on those items?