Ms. Lenfesty knows firsthand how the “fake news” problem affects young people.

In 2015, a decision from the Office of Defamation gave her hope that misinformation on YouTube would one day be regulated by Google, YouTube’s parent company. The California company was created with the belief that journalists could strengthen public discourse.

But Ms. Lenfesty learned soon enough that Google was not as interested in handling misinformation as it was in freeing people’s voices.

Last spring, Ms. Lenfesty helped found the Society of the Responsible Teller, a nonprofit group with 19 members that seeks to create better newsrooms by sharing expertise in journalism, media literacy and online trustworthiness.

But a year later, Google won’t let this group use YouTube as a classroom tool.

“The first thing we said was, we really need to figure out what to do with YouTube,” said Ms. Lenfesty, who then shared the group’s concerns with Project LUNA, a project of Google to work with publishers on identifying and addressing “fake news.”

By the time the Society of the Responsible Teller gathered last week to discuss how the spread of misinformation can best be challenged, Google had barred many of its expert speakers, including Ms. Lenfesty, and any ideas about how to control the flow of misinformation on YouTube.

“We said, ‘Well, Google, you’re really big on press freedom and very aggressive about breaking things. So what are you going to do with this problem?’” Ms. Lenfesty recalled.

Google declined to comment.

Critics accuse Google of promoting memes that confuse the public and sow mistrust of the press and the institutions that try to hold government accountable.

In October, a group of academics from Harvard, Northwestern and other universities presented a report to Google arguing that the way Google surfaces news and other information hurts rather than helps news organizations.

“There is clear evidence that if Google starts to curtail access to YouTube users can no longer find independent, peer-reviewed or accurate content,” the report concluded.

“It could, for example, deprive a key outlet of important funding or material. It could also result in the loss of political or financial power of that outlet,” it said.

One member of the society, Tony Sloan, said Google was encouraging publications to pass along articles, which readers then have to click through to, only as a way to avoid helping the perpetrators of misinformation.

“Google is turning an internet snake oil company into an internet snake oil producer,” said Mr. Sloan, an associate professor of journalism at George Washington University.

Sarah Hill, president of the Society of the Responsible Teller, a non-profit that is also working with Google, said she sees no chance of YouTube changing course this year, as well as no plans for a meeting with YouTube executives.

“YouTube isn’t a new kid,” she said. “This is a very serious problem, and we just want to help Google figure out how to fix it.”