First, open your archive.php from your theme folder. This is a sample code, it can be different in your theme.

Find

< ?php /* If this is an author archive */ } elseif (is_author()) { ?>
<h2>Author Archive for</h2>

And replace with;

< ?php /* If this is an author archive */ } elseif (is_author()) { ?>
< ?php $author = get_userdata( get_query_var('author') );?>
<h2>Author Archive for < ?php echo $author->display_name;?></h2>

After you apply this code the author archive page title will change like “Archive for (author name)“.

That code different in my theme. If you click my avatar in the bottom of this post, you call my author archive page and again you can see author name in the bottom of  page.

That’s All! Have a nice day!

Related posts:

1. Automatically Insert Author’s Bio on each post
2. Highlight the Author Comments!
3. Detect User Browser And Apply A StyleSheet