why doesn't font size match the toolbar?

I copy some text from a document I had written before. The font size was 11 pt. When I paste it into the new doc, it automatically expands it to around 30 pt. I highlight the passage, set the toolbar font size to 11 pt and it doesn’t change. It stays large. What’s happening and how can I override or fix this?

Have you tried first to Format>Clear Direct-formatting or Ctrl+M on the selected range?