Brunom

Pode ser que ajude

1. It will look for any images that you’ve uploaded to your post.

gallery2. If it finds one or more images, it will automatically place the 1st image – as a thumbnail – where it belongs on your site.

Note 1: If you have uploaded multiple images to your post, it will use the #1 image as set in the gallery section of your media uploader (click thumbnail to the right).

Note 2: If you don’t want the image to appear in the post content, just don’t insert it into the post. The plugin will still grab the 1st image you’ve uploaded to the post and place it correctly.

3. If it does not find any images (because you didn’t upload any) for the post, no image will appear for that post in the Featured Article section. As for the post thumbnails, it will place a default thumbnail unless you have deactivated that feature on your Theme Settings page.
Option 2 – Use Custom Fields

If, for whatever reason, you prefer not to use the plugin, you can simply use custom fields. With this method, you will need to scroll down to the Custom Fields section on the Write Post screen and fill in the appropriate data.

For post thumbnail images:

* Name = post_thumbnail
* Value = the URL for the image (get the image URL from the media uploader)

Não esquecer que “key” (Name = post_thumbnail) pode ser diferente, isso depende do template..