Including push-button to thermometer

if (digitalRead(button)) {
  selectedSensor++;
  if (selectedSensor > 3) selectedSensor = 1;
}
switch selectedSensor {
  case 1:
    readSensor(sensor1pin);
    break;
  case 2:
    readSensor(sensor2pin);
    break;
  case 3:
    readSensor(sensor3pin);
    break;
}

Do debounce your button (either in hardware or software - plenty of examples out there). I assume same sensor on all pins, so you just have to provide the correct pin and read that sensor. Change the number of sensors to your number.