Twitter is working on allowing users to clarify old tweets, to follow and mute conversations based on topics, while the company is also improving how it handles abusive content.

“A lot of our work going forward will be around this proactive notion all fueled by machine learning and deep learning,” he said at a Goldman Sachs conference on Thursday in San Francisco. “So we’re making a lot of progress, but we’re not satisfied with where we are because it’s not felt … by our customers.”

For the past couple of years, Dorsey has promised to clean up Twitter. And while the company has made some progress—it deleted tens of millions of fake and other suspicious accounts last summer—it continues to struggle with curbing abusive content.

In a separate interview on Tuesday with tech news site Recode conducted on Twitter, Dorsey said he’d give his company a “C” grade in how its dealt with the issue. On Thursday, he said he believes that artificial intelligence will continue help the company fix its tarnished image, “but it is going to take some time.”

Dorsey also said Twitter is exploring a way for users to clarify their old tweets that they now regret—short of deleting the tweet. This way, users can either add context or explain how they have since changed their minds. The clarifications, ideally, would be tied to the tweet so that the original statement could not be retweeted without the additional context attached.

But Dorsey didn’t make any promises that the feature would ever become reality. “Not saying we’re going to launch that,” he said. “But those are the kinds of questions we’re going to ask.”

Dorsey said, in theory, at least, that Twitter wants to take more responsibility for the impact it can have on people’s offline lives like users getting fired for their controversial posts. He said social networks previously acted as if they had no role outside the digital realm.

When it comes to conversations, Twitter also aims to let users follow or mute conversations by topic. That way if someone wants to chat with other Game of Thrones fans, for example, the conversation is easy to find. Similarly, a user could easily block conversations about Game of Thrones to avoid reading spoilers.

The company is experimenting with this feature using sporting events, allowing users who are watching the same game to tweet in the same space. Dorsey says he hopes to expand that to other categories like entertainment or for people talking about a particular neighborhood, for example.