Be reasonable when using them, use them where they make sense. To quote JohnMu, a Google Employee, from the Google Webmaster Central Help Forum on December 12, 2016, he said, " We don't treat HTML5 differently & having multiple H1 tags on a page is fine. Visual tools are blended into the editor so you get the right amount of help when you want it. Brackets is an open source text editor, lightweight, yet powerful. There's still a lot of misinformation out there about having multiple H1 tags appear on the same page, but rest assured, you don't need to set your posts per page to "1". These editors will help you with your CSS to a greater or lesser degree but they are the starting point for styling.
When that is completed, click on main.less up on the top left. Choose your background image and upload it. It's true, in a perfect world, you would only need one H1 tag per page, but in the real world, multiple blog posts can appear on a main blog page because it's a content management system. Click on 'Edit HTML / CSS' to edit the theme, then click the + button on the left to upload a file. Since we're changing the title of your blog posts to H1 tags, you might be concerned about having multiple H1 tags appearing on your main blog page in order to stay SEO compliant.
To fix this, all we need to do is change a "2" to a "1", and create CSS styling for your blog post titles' new H1 tags. If you use the Weebly blog for the majority of your written content, you're at a slight disadvantage in the SEO department because the titles of Weebly blog posts are currently H2 tags. H1 tags are important for SEO because they tell the search engines what the page consists of.