Where is the SEO title in WordPress?

The input field for your post title – the same as your H1 heading – can be found on top of the page or post editor in WordPress. You can find the input field for the SEO title in the Yoast SEO meta box, which appears underneath the post input field. To edit this title, you need to click on the edit snippet button.

For More Information Please Refer: https://yoast.com/whats-the-difference-between-an-h1-heading-and-the-seo-title/