No, I still have not solved …
The image featured on all pages of the site in my opinion is a mistake because as I said, a site with many uses wordpress plugin
A good theme for a fee in my opinion should have the opportunity to globally set the image out only on all items (or all pages) and then set the individual article if you remove it or not.
Could you tell me a query to launch the database (using phpMyAdmin) to active in all articles already written out featured image?