Zuckerberg was questioned on his statements to Congress in 2024, at a hearing where he said the company did not give its teams the goal of maximising time spent on its apps.
Mark Lanier, a lawyer for a woman who accuses Meta of harming her mental health when she was a child, showed jurors emails from 2014 and 2015 in which Zuckerberg laid out aims to increase time spent on the app by double-digit percentage points.
Zuckerberg said while Meta previously had goals related to the amount of time users spent on the app, it has since changed its approach.
"If you are trying to say my testimony was not accurate, I strongly disagree with that," Zuckerberg said.
During his questioning, Lanier laid out three options of what people can do regarding vulnerable people: help them, ignore them, or "prey upon them and use them for our own ends".
Zuckerberg said he agrees the last option is not what a reasonable company should do, saying, "I think a reasonable company should try to help the people that use its services".
When he was asked about his compensation, Zuckerberg said he has pledged to give "almost all" of his money to charity, focusing on scientific research.
Lanier asked him how much money he has pledged to victims impacted by social media, to which Zuckerberg replied, "I disagree with the characterisation of your question".
Lanier also asked Zuckerberg about what he characterised as extensive media training, including for testimonies like the one he was giving in court.
Lanier pointed to an internal document about feedback on Zuckerberg's tone of voice on his own social media, imploring him to come off as "authentic, direct, human, insightful and real", and instructing him to "not try hard, fake, robotic, corporate or cheesy" in his communication.
Zuckerberg pushed back against the idea that he's been coached on how to respond to questions or present himself, saying those offering the advice were "just giving feedback".
Regarding his media appearances and public speaking, Zuckerberg said, "I think I'm actually well known to be sort of bad at this".
His appearance at the jury trial in Los Angeles, California on Wednesday, local time, was the billionaire Facebook founder's first time testifying in court on Instagram's effect on the mental health of young users.
Meta may have to pay damages if it loses the case, and the verdict could erode Big Tech's longstanding legal defence against claims of user harm.
The lawsuit and others like it are part of a global backlash against social media platforms over children's mental health.
Australia has prohibited access to social media platforms for users under age 16, and other countries including Spain are considering similar curbs.
The case involves a California woman who started using Meta's Instagram and Google's YouTube as a child.
She alleges the companies sought to profit by hooking kids on their services despite knowing social media could harm their mental health.
She alleges the apps fuelled her depression and suicidal thoughts and is seeking to hold the companies liable.
Meta and Google have denied the allegations and pointed to their work to add features that keep users safe.
Adam Mosseri, head of Instagram, testified last week he was unaware of a recent Meta study showing no link between parental supervision and teens' attentiveness to their own social media use.
Meta's lawyer told jurors at the trial the woman's health records show her issues stem from a troubled childhood, and that social media was a creative outlet for her.
With AP
