When I was a kid, my old English text book told me that we could response to "Thank You" with "Not At All", which means you are welcome. But when I answer two of my American friends with this phrase" NOT AT ALL" when they thanked me , in different times of course, they didn't quite know what I was talking about. After I told them everything about this phrase, they told me that that phrase could be used only when you don't accept someone's thank, that means you reject their thank unpolitely.

But in today's dictionary or some place, as well from Chinese friends' mouth, I could sometimes still get that phrase as "YOU ARE WELCOME".

How do you know about that, friends. Could you help me with that?

A lot of thanks to you guys.
I think this is primarily a British expression. As I understand it, it means something like "no trouble at all" and is normally taken to mean "you're welcome".
Tell them it's a far nicer version of "No problem." (A pet peeve of mine. I really dislike it intensely when I say "thank you" to a waiter or someone behind the counter of a store and get "no problem" in return.")

Other alterntives:

My pleasure. // It was my pleasure.

Happy to do it. // I'm glad I was able to help.
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Thanks man. I got it. Now I know someother answers of thank you. The only thing I don't quite understand is why my two friends don't know that sentence.
or you can say >>>>Don't mention it.
As a native I dislike people saying man... Thanks would do just fine. About your friends, if they are native speakers and don't know the expressions then it's a possiblility they come from a different state and might not use them. All natives don't have to know every expression! Do you know every expression in your language?
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