Only Displaying Administrator

First let’s determine for sure which author is actually stored in the DB. Because almost any output in WP can be filtered and altered, we should go to phpMyAdmin to investigate. The posts table lists the author ID for every post. The original administrator’s ID from when WP was installed should be 1. Double check by looking at the users table.

If all the author IDs are for the administrator user, the selected author you’ve added is not saved as the true author. If it were saved in postmeta instead, you cannot use the_author() to display this value, it would need to come from get_post_meta().

If the stored author IDs are all correct, a plugin or your theme is somehow altering the output of the_author(). Narrow down the source by deactivating all plugins and switching to a default twenty* theme. The correct author should now be listed. Begin restoring your setup, one module at a time. When the author output becomes incorrect again, the last activated module is the culprit.

BTW, the_author_meta(‘display_name’, 1); will always return the administrator’s name because you are passing the user ID 1 to the function 🙂 The ID needs to come from the post object. “author” in this case is a misnomer, it really ought to be the_user_meta().

Saving the “author” in post meta would be a reasonable option, but you’d need to use custom code to display this value. “the_author” filter can be used for this. To save the selected drop down value to post meta, use the “save_post” action. Get the drop down selection from the $_POST array (keyed by field name) and save it with update_post_meta().

Be sure to coordinate the data type passed in $_POST with the one used in “the_author”. If they are all the username, then you’re good. If the user ID is somehow involved instead, you’ll need to get the user object with the ID to work out the name.

Alternately, you could set the actual post_author field to the selected user’s ID in the “wp_insert_post_data” filter. I’m not too keen on this approach because you lose track of who actually created the post. I generally don’t like to destroy data even if it seems to not matter at the time. YMMV

I’m happy to keep you pointed in the right direction, but I’m not able to completely line everything out for you either. If you can typically self-learn things with some direction, this can work. Otherwise you would be better off utilizing a resource than can devote their full attention. Such as hiring help through something like jobs.wordpress.net or jetpack.pro.

While getting values out of $_POST and saving them is the normal approach and can solve your problem, I’d forgotten that the “pseudo” author values are showing up on the admin posts list screen. Thus the data is clearly saved somewhere and re-saving the same value for yourself elsewhere is redundant, inefficient, and just poor practice. Apologies for my lapse. You should make a concerted effort in determining how this is accomplished before working on saving the value yourself.

How did this author metabox and the pseudo authors in the author column come to be? A plugin? Your theme? Where the data is stored can be determined by examining the existing code. Often easier said than done. Unless there is a custom table for such information, post meta is the logical place for this. It could conceivably be stored as an array of post IDs in user meta, but that would be very impractical. I think it’s in post meta, you’ve just failed to recognize it so far.

If you were looking for author names, it could be the data was saved as user ID. It could also be stored in an array of other data, making searching a bit more difficult. I’d recommend making a concerted effort to find where the data is stored before re-saving it with your own methods. Utilize phpMyAdmin and as needed, the LIKE %…% operator while searching post meta. This will find data in serialized arrays as well as stand alone values. Try looking for the user ID as well as the various possible names associated with users. Using LIKE %…% with single digit IDs will likely yield a lot of false positives though. Use discretion.

If you can determine where this data is stored, using “the_author” filter will be a lot easier. I’ll skip over instruction for saving values in $_POST for now since it’s not necessary if the data can be found. Read up on filter and action hooks in general in the Plugin Handbook. Also check out get_the_author() source code to see how “the_author” filter is actually applied and the return value used.

This particular code uses the ternary operators, which is confusing if you’re not familiar with it. Here it is used as a safety valve to prevent code from throwing warnings in the off chance $authordata is not an object. In general $authordata will always be an object, so the statement without the ternary logic would simply be:
return apply_filters('the_author', $authordata->display_name );

When you hook this filter, your callback function is passed $authordata->display_name, which in your case, will always be that for admin user ID 1. Whatever is returned by your callback is then returned by the apply_filters() call, which in this case is returned by the get_the_author() call. In many cases the return is assigned to a variable instead of immediately being returned.

What’s with get_the_author() when you are trying to use the_author()? It’s called by the_author(). As is often the case, check out the source code. The logic here is a little confusing because of the deprecated parameter. The default case is what is returned from get_the_author() is immediately echoed out. It’s possible to cause the value to be returned instead, but then we should simply call get_the_author() directly if that is what we want.

It should now be clear the goal of your callback is to return the display name of the user stored as the pseudo author of the current post. But what’s the current post? An important tenet of PHP is all variables within a function are local to the function. Outside variables are not available within the function and variables within the function are not available outside. One of the few exceptions are global values. Since the_author() is always used in the Loop, the current post is stored in the global $post. Anytime you wan to use a global, you must declare it within the scope of its use. Thus your callback must contain this statement: global $post;

With the current post, get the stored pseudo author for it and return their display name. You’ll likely need to do some intermediate steps, like getting the ID property within the $post object and maybe getting the display name based on the user ID. You should be able to find out how to do such things by searching. If you have trouble with anything, let me know. Good luck!