Log into your WordPress back office and find this:

Click the "Editor" button.

Now from our previous investigating we know that the "Menu <h1> tag" is located in the "Header" and the "Previous <h1> tag" is located in the "Post Naviagtion" aka "Theme Function" section.

Now the tricky part!

Caution: These types of changes will be erased when a theme is updated. Also if you mess something up you may irreparably break your site. To avoid both issues you would want to create a Child Theme first and make the changes within the Child Theme.

Let's do the "Header" first. Scroll down till you find this.

Simply replace the "h1" with a "h2" or "h3". What ever you like just not a "1".

Click Update.

We will do the same thing in the "Theme Functions".

Simply replace the "h1" with a "h2" or "h3". What ever you like just not a "1".

Click Update.