Hope you are having a good day and thank you for your question
this is not the problem you can include your custom h1 title text in the post editor, default page title uses h2 tag and unfortunately, there is no option to change this without customization of the template files
I’m approaching this from an SEO pov. Ideally each page should have one H1 as the main header at the top of the page. If the shapely theme doesn’t allow that then I’ll stick with the set up I’m using now.
On the other subject of the home page. Do you know why theme only seems to be working when I’m logged in as admin?
You can have one h1 on the page, it not required to stick it at the top of the page because its not possible, there is a menu and other text above it so this is not required in SEO, just use one h1 tag on the page,
The subject of having Blog Post Titles as a H1 has come up again and I really do need to change from the H2 to H1.
How do I customize the template file to do this?
“How do I customize the template file to do this?” - customizing theme files is outside of our free support, this is up to our clients, usually, if you don’t have experience with this you have to hire someone,
easy thing i can suggest (but you must have some experience) is this plugin to know which theme file was used for page and then you have to edit it: https://wordpress.org/plugins/what-the-file/