Oh lordy, this is ripe for a refactor, but I can't quite see it...

refactor.rb

    case service_time.relation_to_sunday
    when "Current"
      previous_sunday
    when "Before"

      if date.wday == service_time.day_of_week
        #use date and time
        actual_service_time = service_time_with_offset(service_time, date, true)

        if time >= actual_service_time
          return upcoming_sunday
        else
          return previous_sunday
        end

      elsif date.wday > service_time.day_of_week
        return upcoming_sunday

      else

        return previous_sunday

      end

    when "After"

        if date.wday == service_time.day_of_week
          #use date and time
          actual_service_time = service_time_with_offset(service_time, date, true)

          if time <= actual_service_time
            return previous_sunday
          else
            return upcoming_sunday
          end

        elsif date.wday < service_time.day_of_week
          return previous_sunday

        else

          if church.service_times.where(relation_to_sunday: "Current").empty?
            return previous_sunday
          else
            return upcoming_sunday
          end

        end

    end

if time >= actual_service_time
   return upcoming_sunday
else
  return previous_sunday
end

Could become :

return upcoming_sunday ? time >= actual_service_time : return previous_sunday

Which you could maybe make a method to be reusable?

Person.update_all(plan_permissions: 5) That should do it!