It woud depend on how you activated the hide footer option. I’ve not had muchexperience on mutiple products. If you used the Weaver Xtreme per post option on each and every product as you edited/created them, then the only way to undo that is to do it that way again – undo it for each and every product/post.
If you did it using the global option, then you should just be able to undo that one setting.
A link to your site with specific examples of posts you need to change would be helpful.