You ask this all the time
Formerly LadyCeres

It was changed by the American publisher, Scholastic, because it thought American children wouldn't want to read a book with "philosopher" in the title.
How rude!

To go with the rocks in the heads of many Americans.
Norman! What did you put in my tea?

I’ve mentioned this before I think, but as an American, even the title change to Sorcerer’s Stone wasn’t enough. The movie title should have been changed to “Wizard Kid and the Magic Rock”. Now that’s something I can understand!

Because most Americans are dumbed down and
more stupid
than the rest of the world.
The name was thought to sound too archaic, so the American edition was published under the title J.K. Rowling suggested, Harry Potter and the Sorcerer's Stone.
My password is password

Because most Americans are dumbed down and more stupid than the rest of the world.
Norman! What did you put in my tea?

The latter does sound better. Maybe it's because US children never heard of a philosopher's stone. I know I hadn't. The whole alchemy thing is like magic, and nost of us have heard of sorcerers doing magic. That's my guess.
ᴳᵒ ᶠᵘᶜᵏ ʸᵒᵘʳˢᵉˡᶠ