It depends on what you want to change! If you are talking about the general details that apply to all recurring events then you probably mean you want to change the set-up details as held on the series. For example, it's name.
An event series holds many details that apply from one recurring event to the next and you'll be able to choose it in Manage series. Select the Update tab and make whatever changes are required. The Update tab shows a lot of details and this article will help you understand each one. If you are unsure of what to change then refer to your Events manager for guidance as they will have set the series up in the first place.
The key aspect of a single event is the date range during which the event occurs. This can be changed in Manage Events by selecting the Details tab.
Otherwise, you might be talking about the draws in the event or the joiners - these can be reviewed and changed in Manage draws.