Updating to the latest version

What version of WordPress are you running? With any recent version you should be prompted for an automatic update.

The existing credits won’t be affected but the update (meaning both the embedded shortcodes in the post content and the credits associated with attachments).

I’m using WordPress 4.2.

Than you should see the update available in Updates section on the admin backend. Is it not there?

No, it’s not there. That’s why I asked my original question.

Have you by any chance disabled auto updates in wp-config.php (or via some filter)? Did you recently upgrade your WP installation?

In any case, to manually update the plugin without deleting your Media Credit options (though not the credits themselves), you have to delete the plugin directory <path_to_wp>/wp-content/plugins/media-credit/ and upload the ZIP file via Plugins > Add New.

Did the procedure work?

I haven’t tried it yet. But, I just want to make sure: If I do as you suggested, I won’t lose the media credits that are on my site, right?

No, you won’t lose anything. Neither the post content nor the post meta data will be changed.

Did it work?

I updated the plugin as you suggested. The update worked and I didn’t lose any of the media credits I had added with the previous version of the plugin.

However, I soon discovered a different problem. When I added an image to a new post using the Add Media button, my Media library opened, I selected an image and it appeared in the post box. But when I clicked on the image to edit it, the edit options did not appear over the image.

I contacted my host, a WordPress specialist, and they identified the Media Credit plugin as the cause of the problem. I deactivated the plugin and I was once again able to edit images within posts.

So, for now, I am not using the Media Credit plugin. Maybe others have experienced this as well? I thank you for your responses to my questions.

You mean this toolbar doesn’t appear? (It doesn’t quite look like the linked screenshot anymore, but near enough.) Did you clear your browser cache?

While on general principle I would advise you to update to 4.3.x, the plugin should work with 4.2, including the edit image toolbar. What’s the exact version of WP you are running? I just tried the latest version of Media Credit with a clean install of WordPress 4.2.5 (the last security release of WP 4.2) and the toolbar does popup as intended.

@kegarne: Were you able to resolve the issue?

I appreciate your follow-up on this. The only way I was able to resolve the issue was to deactivate the plugin. It may be a conflict with another plugin, I’m not sure.

Could you please post your exact WordPress release? And is it about the toolbar in the linked screenshot? Just so that we are talking about the same thing.

Yes, it is the issue in the screenshot. I am running WordPress 4.1.7.