Post titles how in H1 – how do I change to H2?

Hello

My page titles (H1) are set to white as they are against a pink background strip. POST titles used to show up in blue in the content area, underneath the same post title in white against the pink background.

For some reason, post titles settings have changed and are now also white (so I assume now H1) rather than blue. Is it possible to fix it that post titles are H2 instead of H1, but that page titles stay in H1?

See this page for example: https://www.lovemusic.org.uk/our-teams-playlist-20th-april-2020/ – if you treble click above the content, in the white space, you’ll see the post title is lurking there.

Thanks for your help. R