SEO Title not displaying properly
If your website page title is not displaying as per your WordPress SEO then you probably have an issue with your Theme header.php setup. Largely this is down to bad WordPress website development which typically manifests in the page title being manually typed, rather than using the correct wp_title() format for WordPress and your SEO plugin (like Yoast SEO, Premium SEO) to target for SEO updates. If the SEO title on all of your posts/pages/custom posts is the same, or not what you are inputting into your SEO plugin and your SEO rankings have plummeted, then you are probably affected. To fix this go ahead and open your WordPress site's header.php file and look at the 'head' tag at the top of the file for:-
Now the SEO plugin can use the wp_title WordPress hook to inject the correct SEO page titles into the Page / Post / Custom Post Titles
WordPress doesn't actually need the wp_title() title element
As of 2015 wp_title() was no longer a requirement so theme modern themes don't actually include the wp_title() in header.php files and that includes the full/surrounding 'title' element. However what they do require is title-tag support.Most themes already add 'title-tag' support, but if you have an old one then run a check to ensure that your site has title-tag support. Open up your theme's functions.php file and search for 'add_theme_support( 'title-tag' );'
If the WordPress theme does not have 'title-tag' support then add the following to the theme's functions.php:-
Hopefully, via one of the above methods, your SEO title problem is solved and you can now get your SEO back on track, but if it doesn't then use a recommended WordPress SEO plugin like Yoast SEO that includes a Force Rewrite option.