Discover device after adding it by mqtt

After adding the device correctly to assign it to a person that device must first be previously discovered. How can I make the device appear?

mqtt:
  broker: 192.168.0.160
  port: 1883
  username: manny
  password: 4567
  discovery: true
  discovery_prefix: homeassistant

switch:
- platform: mqtt
  name: "Sonoff Switch 01"
  command_topic: "cmnd/sonoff1/power"
  state_topic: "stat/sonoff1/POWER"
  qos: 1
  payload_on: "ON"
  payload_off: "OFF"
  retain: true
  device:
   identifiers: 1
   name: Switch1

What does this mean?

Delete the switch configuration and set option19 in the sonoff.

Once the devices appear, I can assign them to the different users that I have created in Home assitant but for this I must previously make them appear to me

But it is not a code error?