How Do Is Say Thank You For A Best Answer?

[xanthoma]

That's all. How do I say thank you?

[Cloverjo]

You can say it on the same thread for which you were given best answer.

[fiction-factory]

I mentioned how on your earlier thread.
Just do what you've done before
eg https://www.theanswerbank.co.uk/Quizzes-and-Puzzles/Crosswords/Question1675737.html

[fiction-factory]

xanthoma means for an answer she has received to her question.
As well as replying with a thankyou you can click the "mark as best answer" button if it's on your question