I had a Wordpress site with theme downloaded from Internet. When I used Bing Webmaster tool to view SEO Reports (under "Reports & Data" > "SEO Reports"), Bing complained that I had too many H1 tags on each page. For those familiar with HTML, H1 tag is one of the six header tags (h1, h2,..., h6) to be used in HTML body. H1 is usually used as the top level title. While there is a debate going on such that there is nothing wrong to have multiple H1 tags in a page, Bing is just not so happy about it and returns 2.6K error counts on my site!
The solution is pretty straightforward: open your favourite code editor and modify the code. Keep only one H1 tag in a page and change the rest to e.g. h2, h3,..., h6. Do this on test machine. Load the page and view its source code from browser (e.g. From Chrome, right-click on a page > "View page source"). Make sure only one H1 appears on each page before uploading your code to production server. For my case, I set my site name as H1 when users land on my main page (e.g. <h1>Little CPU - Description goes here</h1>). When users nagivate to an article, H1 is now my article title (e.g. <h1>SEO Tips #02 - Removing Multiple H1</h1>).
Make sure you clear your cache and if you are using CloudFlare, temporary enable development mode to disable caching. Bing's SEO Reports run every other week so you have to wait for the changes to take effect.