Quote Originally Posted by ZhaneX View Post
I think this is more just people misunderstanding how the Wondrous Tails book itself worked. That is, they thought that a particular duty would be tied to a particular sticker, or that using retry would remove a sticker. This is not the case. Thus, retry doesn't swap stickers around or remove one, but just lets you redo a task you've already done to earn another sticker, while counting another duty you've yet to do as "Done" to account for the stickers you already have.

So of course you wouldn't be able to use it once you have all 9 seals.
This is exactly how me and my bf understood it. I was lucky enough not to have gone crazy with the stickers yet, but he pretty much wasted his book for this week because of the misunderstanding. More clarification for how Retry works in any in-game capacity would help out a lot.