There's a lot of content on YouTube, which is why the site tries to shepherd you towards the most relevant videos via its recommendations. These hints are based on your search and viewing history, so they can be thrown off if someone borrows your laptop or you have a sudden binge on lengthy unboxing videos. With that in mind, here's how to view and manage your history on YouTube.
You can access the relevant screens through your Google Account History page (click Manage History under the YouTube headings) or by going to www.youtube.com/feed/history directly (assuming you're signed in of course). The two tabs at the top of the page let you switch between the videos you've watched on YouTube and the words and phrases you've searched for... you'd forgotten your Pavement phase, hadn't you?
Individual items can be removed via the buttons to the right, or you can click one of the Clear all buttons to wipe everything and start again from scratch. There's also the option to pause the history feature, which can come in handy if you need to research the migration patterns of South American birds but don't want these clips interfering with future recommendations.