In this release, we have implemented a new option to set the number of posts in the thread to search for an automatic thumbnail. The option is one by default, so product's behavior does not change after installation and only the attachments and images in the first post are considered.
We have also implemented an option to limit the posts parsed to thread starter's posts only. This way only thread starter will be able to set the thumbnail but will be able to do so by just posting another reply containing the image/attachment.
The new version is available for all licensed customers at
https://customers.addonslab.com/marketplace.php/my-services/
Feel free to suggest further enhancements for the add-on or report any issues you have and they will be addressed asap.
Please consider posting a review if you are using the add-on and let us and other users know how it works for you.
Thank you!