You definitely can update the template to change this to be a <h1> tag instead of an <h2>. You would need to turn your site on for developer mode, pull down the code, change one line of code (change line 14 or blog.item to be an <h1> instead of an <h2>), then commit that back to your site.
If you are still trying to fix this reach out to me if you are running into any issues.