If you go to the end of the comments, you can thank everyone as if you were answering your own question, in the comment box. Then everyone who has commented will see it.

This works because if you look at the top of the page where it says Hi Tadpole, Your Options, click on that and choose Your News you can see a list of all the questions you have asked and all the things you have commented on. If you then click on the one you want it takes you to the original question, where you can add another comment if you wish.