A master list of contacts is stored in the Contacts section of the Event Manager App.
To view or edit contact details:
Go to the Event Manager App > Contacts section > Contacts tab.
Select a contact and click the Edit button.
The Edit contact dialog will appear allowing the contact details to be updated.
Note that Sync on Registration setting controls how this record will be updated if the contact registers with your event. More details here.
Click OK to save your changes.