Appearance → Customize → Archive. Four settings work together here: Show categories, Category position, Show author and Show author avatar.
Categories
Show categories prints the post’s categories. Category position decides where:
| Next to the meta (date, comments) | the default — the categories join the meta row under the excerpt |
| Above the post title | the categories are printed on their own line above the headline |
Above the post title is the news-site arrangement: the category reads as a section label — CULTURE, POLITICS — and tells you what kind of story is coming before you read the headline. Next to the meta keeps the row compact and treats the category as filing rather than framing.
The position setting does nothing when Show categories is off.
The single post has its own pair of these settings, so a listing can label sections while the article itself does not.
Author
Show author is off by default — it changes how every existing listing reads, so it is opted into rather than out of.
Turn it on for anything with more than one writer. A byline on a single-author blog is noise; on a news site it is part of the story.
Show author avatar adds the writer’s face before their name. It is a no-op when Show author is off, and also when avatars are switched off site-wide at Settings → Discussion → Avatars.
Avatars come from WordPress, which means Gravatar, which means an external request per distinct author. On a site that takes its no-third-party-requests seriously, leave avatars off in the listing and keep them for the author archive, where there is one.
The order in the meta row
Categories, author, date, comment count — always that order, with the missing ones closed up. It is not configurable.
On an author archive
The author archive puts the writer’s avatar above their name and bio at the top of the listing, drawn at 72px from a 144px file so it stays sharp on a high-density screen. That is separate from Show author avatar and needs no setting; it appears whenever site-wide avatars are on.