Blog Post Titles Showing as H2 instead of H1

Hello. When I run an SEO audit it shows that my blog posts are missing H1 tags. To verify this, I right-clicked the title of one of my blog post and hit inspect, which confirmed that my blog post title is wrapped in an H2 tag (see below snippet).

.....<h2 class="gb-headline gb-headline-56c7eb13 gb-headline-text">Affirmations for Confidence</h2>.....

How do I change all my blog post titles to H1? Do I need to create a hook to do this? If so, what code would I use.

Thanks in advance!