So it is known as that The Protocols of the Elders of Zion has been exposed as a fabricated antisemitic text by the British newspaper The Times in 1921 and the German Frankfurter Zeitung in 1924. Yet, when the Nazis came into power in 1933, it is taught in German schools as if factual. What did the Nazi have to say about their antiseptic text being exposed as a fraud? Do they just shrug it off as just some left wing or Jewish newspaper trying to dispel the myth that Jews aren’t a dangerous race in their propaganda? Or are there more reasons behind the fact that it was used in schools and even neofascist, fundamentalist and antisemitic groups to this day?
Hitler and Goebbels knew it was a forgery well before the Nazis ever came to power; Goebbels mentioned this in his diary as early as 1924 and Hitler noted the claims that it was a forgery in Mein Kampf. Hitler pointed out that the media (particularly the Frankfurter Zeitung) claimed the Protocols were fakes, which he said proved the "inner truth" of the documents, even if they weren't authentic. Hitler never mentioned them publicly and they weren't really a part of Nazi propaganda, even if Hitler believed they had a kernel of truth to them.
However, it was promoted in Nazi education (alongside other books, such as Alfred Rosenberg's The Myth of the Twentieth Century), and they were published and disseminated with the Nazi Party's support. They were also used by some Nazi propagandist publishers, most notably Julius Streicher of Der Stürmer. These types of publications were generally targeted toward the common people rather than the intelligentsia, who would have been aware the Protocols were a forgery. The Propaganda Ministry, however, generally stayed away from them, apparently because they didn't believe they were useful; this may have been because Goebbels was aware they were a forgery and it could hurt their credibility to use something that was known to be inauthentic. Nonetheless, it was translated and published in several languages in occupied Europe as part of the Nazis' propaganda efforts in those territories.
So, essentially, the leading Nazis knew they were fake, but only cared about that insofar as it hurt the credibility of their antisemitic public message. When they thought it was useful, particularly in dealing with younger, more impressionable audiences or groups of people they considered less intelligent, they used it, since it aligned with their claims of a global Jewish conspiracy. When they were producing content for consumption abroad or among the German and international intellectual community, they stayed away from it because they knew it was forged, and knew that their audiences would also know that, so they didn't want to undermine their own credibility. It was very much a utilitarian approach, and they had no illusions about the actual veracity of the Protocols.
Source: Randall L. Bytwerk, "Believing in 'Inner Truth': The Protocols of the Elders of Zion in Nazi Propaganda, 1933–1945," Holocaust and Genocide Studies 29, no. 2 (Fall 2015): 212–229.