Formatting gone haywire

I made 1 change and now when i look at the new document…the entire doc is screwed up…where a bunch of text is bolded
I see that these areas have a different definition of Default Text (instead of Arial 9.5 it has Arial 9 with Bold)
I DID NOT CHANGE THAT in hundreds of sections.

How can I FIX this document…without going to hundreds of sections and reformatting.

Default Text is a style that you accidentally changed. Change it again. Probably this and this will help.