Designations of directors by name or number have no significance whatever after election and qualification of the directors or after appointment and qualification of a director appointed to fill a vacancy, but merely fix the designation and status of each such office as a separate office for the purpose of nomination and election thereto, or for filling a vacancy. Sections 15953 to 15960, inclusive, apply to the election of the first board of directors of the district, as well as to all elections of directors held by the district.