Thank yous or Thank-yous is the plural of Thank you when it is used as a noun. Thank yous is usually a section of a speech or piece of work when you want to show your gratitude to other people who took part in the project.
Why is Thank you’s incorrect?
We use an apostrophe when we want to show possession.
This is Kate’s house
Peter’s car is very fast.
In this situation, we use Thank you as a noun and it is not in possession of anything so there is no need for an apostrophe.
When do we use Thank yous?
Thank yous is a section of a book that is also sometimes acknowledgments. This section usually shows people who were involved in helping the author finish the book and often includes the people who gave the author feedback.
Hyphen or no Hyphen? Thank-yous or Thank yous?
Thank-you is a noun that comes from a verbal form(to thank somebody). In this case, you should use a hyphen but in normal everyday English, it is also correct to say Thank yous.