“Thee” and “thou” in “The Lord of the Rings”

[Galadriel55]

Originally Posted by Guinevere

When reading "The Children of Húrin" I noticed that Christopher Tolkien had changed all the "thou"s to "you"! (in the conversations with Glaurung and Gurthang) Why do you think he did that?

What?! No!!! I never noticed that before. And now it all sounds wrong in COH.

I can't think of any reason CJRT would want to change it. But another question is why he changed it in COH but not in The Sil. He edited both of them, so why not change both, or leave both?