Your YouTube history tracks the videos you search for and watch to improve the accuracy of its recommendations. You can delete specific videos, clear your entire history, and turn off Google's ability ...

YouTube History makes it easier for us to find and play videos we like or prefer watching repeatedly. But, if this feature concerns your privacy, you can control it by deleting or pausing your history ...

YouTube could slow down sometimes without you knowing because of the website and app caches. If this is enough to bother you, then you might want to clear them on your phone or desktop right away.