A tenancy is associated with a tenant. You must therefore identify and select the required tenant:
From the resulting view of tenant details select the "Tenancies" tab. This tab will list all tenancies associated with the tenant(if any). Then...
- Identify the required tenancy
- Click on Action "Edit" (Pencil Icon) to the right of the identified tenancy
You may make changes at this point, then select "Update Tenancy" or "Cancel" if no changes have been made.