You can do this in two ways.
When creating a new tenancy, you can edit any details within the Offer form as you go along. You’re prompted to review the details of the Offer in the Offer Summary before you press “Send offer.”
Once the tenancy has been created, you can edit certain information from the Tenancy Overview page. In the bottom right of the screen, you’ll see the information you provided when creating the tenancy. Anything that is editable has a pencil symbol next to it. Click the pencil to edit the details.