How do I change the name of a segment?

On the page Subscribers → Segment, you can find an overview of all segments you have made for a specific list. You get to this page by selecting the relevant list on the Subscribers page, for instance by clicking 'View'.

In this overview, you can click Edit (for the relevant segment). You will then be directed to a new page, where you can change the name of the segment. On this page, you can also edit the definition of the segment, or delete it.