I am indebted to Brandon on Stack exchange for this answer
Sometimes the blog-related styles don't show up by default, and you cannot search for them. To ensure that they appear:
navigate to your blog page first (the page with the metadata you want to change), while logged in and editing your site.
Then, go to Design > Site Styles.
At this point, the blog-related style settings should be in the list; you can search for them by typing "blog" in the search field in the sidebar. Alternatively, click on the area of the web page that has the blog meta and the settings should appear in the sidebar.