The Google-owned firm was alerted to the fact that several disturbing videos had appeared on the app that were not suitable for children, including one which explained how to sharpen knives.
Responding to the issues, YouTube told the BBC: "We have seen significant investment in building the right tools so people can flag that [content], and those flags are reviewed very, very quickly.
"We're also beginning to use machine learning to identify the most harmful content, which is then automatically reviewed."
Google acknowledged that its desire to ensure that YouTube remains open brings "real challenges because the content is uploaded and it is live".
YouTube added: "It is a difficult balance to get right. It is a difficult environment because things are moving so, so quickly."
Meanwhile, it was recently announced that YouTube is to stream the 2018 BRIT Awards for the fifth consecutive year.
The annual award ceremony will take place at London's O2 Arena on February 21, and will be aired live on ITV in the UK.
However, fans from around the globe will also be able to tune in to the action via YouTube, which will be offering a worldwide live stream of the event.