[THEME: ATAHUALPA] Titles Are Different Sizes On Single Posts

The titles on my site are perfect: https://financialnerd.com/

However, on single posts (https://financialnerd.com/how-to-avoid-major-food-price-increases/) the titles are bolded and larger.

I’ve searched everywhere and can’t figure out how to change it (or how this happened to begin with).

I’m also having a similar issue below the post: “1 comment to How To Avoid Major Food Price Increases” – where can I change the text and styling for that? Couldn’t find it in the theme options.