
Perhaps some authors quoted an English translation which caused the variation. All anyone can do is use what RS publish. Our Quote section changes frequently, so there is really not enough time to prepend or follow-up on the exactness of a quote, especially if it's not a recorded original, or it was not written by the speaker...which is why it's referred to as a quote. There is no way to possibly know if the author quoting a person actually got verbatim.
WikiQuote delves into it in more detail: A new type of thinking is essential if mankind is to survive and move toward higher levels. From "Atomic Education Urged by Einstein", New York Times (25 May 1946), and later quoted in the article "The Real Problem is in the Hearts of Man" by Michael Amrine, from the New York Times Magazine (23 June 1946). A slightly modified version of the 23 June article was reprinted in Einstein on Peace by Otto Nathan and Heinz Norden (1960), and it was also reprinted in Einstein on Politics by David E. Rowe and Robert Schulmann (2007), p. 383. In The New Quotable Einstein (2005), editor Alice Calaprice suggests that two quotes attributed to Einstein which she could not find sources for, "The significant problems we face cannot be solved at the same level of thinking we were at when we created them" and "The world we have created today as a result of our thinking thus far has problems which cannot be solved by thinking the way we thought when we created them," may both be paraphrases of the 1946 quote above. A similar unsourced variant is "The world we have created is a product of our thinking; it cannot be changed without changing our thinking." In the 23 June article Einstein expanded somewhat on the original quote from the 25 May article: Many persons have inquired concerning a recent message of mine that "a new type of thinking is essential if mankind is to survive and move to higher levels." Often in evolutionary processes a species must adapt to new conditions in order to survive. Today the atomic bomb has altered profoundly the nature of the world as we knew it, and the human race consequently finds itself in a new habitat to which it must adapt its thinking. In the light of new knowledge, a world authority and an eventual world state are not just desirable in the name of brotherhood, they are necessary for survival. In previous ages a nation's life and culture could be protected to some extent by the growth of armies in national competition. Today we must abandon competition and secure cooperation. This must be the central fact in all our considerations of international affairs; otherwise we face certain disaster. Past thinking and methods did not prevent world wars. Future thinking must prevent wars.
Interview with Alfred Werner, Liberal Judaism 16 (April-May 1949), Einstein Archive 30-1104, as sourced in The New Quotable Einstein by Alice Calaprice (2005), p. 173
Differing versions of such a statement are attributed to conversations as early as 1948 (e.g. The Rotarian, 72 (6), June 1948, p. 9: "I don't know. But I can tell you what they'll use in the fourth. They'll use rocks!"). Another variant ("I do not know with what weapons World War III will be fought, but World War IV will be fought with sticks and stones") is attributed to an unidentified letter to Harry S. Truman in "The culture of Einstein" by Alex Johnson, MSNBC, (18 April 2005). However, prior to 1948 very similar quotes were attributed in various articles to an unnamed army lieutenant, as discussed at Quote Investigator : "The Futuristic Weapons of WW3 Are Unknown, But WW4 Will Be Fought With Stones and Spears". The earliest found was from “Quote and Unquote: Raising ‘Alarmist’ Cry Brings a Winchell Reply” by Walter Winchell, in the Wisconsin State Journal (23 September 1946), p. 6, Col. 3. In this article Winchell wrote:
Joe Laitin reports that reporters at Bikini were questioning an army lieutenant about what weapons would be used in the next war.
“I dunno,” he said, “but in the war after the next war, sure as Hell, they’ll be using spears!”
It seems plausible, therefore, that Einstein may have been quoting or paraphrasing an expression which he had heard or read elsewhere.
https://en.wikiquote.org/wiki/Albert_Einstein
See also http://quoteinvestigator.com/2010/06/16/future-weapons/
http://www.amazon.com/New-Quotable-Einstein-Alice-Calaprice/...
(I have checked the preceding edition)
http://www.amazon.com/Quotable-Einstein-Albert/dp/0691026963...
to see if that is a genuine Einstein quotation? In the English-speaking world, Einstein is second only to Mark Twain in having sayings attributed to him that he never said.
http://www.amazon.com/Quote-Sleuth-Manual-Tracer-Quotations/...