ESP32 LoRa settings are not applied - c

Question

I use this board from Heltec automation, which has LoRa and an OLED display onboard.
I do not use the Heltec library, instead I use the lora.h library directly.
When I want to adjust the spreading factor and transmitting power, these settings are not applied and there is no change in the signal. Also I have read different registers regarding spreading factor and transmitting power before and after setting and there is no change.
In summary, when I try this, nothing happens.
LoRa.setTxPower(20);
LoRa.setSpreadingFactor(12);
The code:
#include <Arduino.h>
#include <LoRa.h>
#include <Wire.h>
#include <SSD1306Wire.h>
SSD1306Wire display(0x3c, SDA_OLED, SCL_OLED, GEOMETRY_128_64);
const int csPin = 18; // LoRa radio chip select
const int resetPin = 14; // LoRa radio reset
const int irqPin = 26; // change for your board; must be a hardware interrupt pin
String outgoing; // outgoing message
byte msgCount = 0; // count of outgoing messages
byte localAddress = 0xBB; // address of this device
byte destination = 0xFF; // destination to send to
long lastSendTime = 0; // last send time
int interval = 2000; // interval between sends
int msgLoopCounter = 0;
void setup() {
Serial.begin(115200);
while (!Serial);
// Set OLED reset pin to HIGH
pinMode(RST_OLED, OUTPUT);
digitalWrite(RST_OLED, HIGH);
delay(1000);
// Initialze OLED display
if (!display.init()) {
display.setContrast(255);
display.clear();
display.display();
while (true);
}
Serial.println("Display init succeeded.");
// Initialize LoRa
LoRa.setPins(csPin, resetPin, irqPin); // set CS, reset, IRQ pin
LoRa.setTxPower(20);
LoRa.setSpreadingFactor(12);
if (!LoRa.begin(868E6)) {
Serial.println("LoRa init failed. Check your connections.");
while (true);
}
Serial.println("LoRa init succeeded.");
}
void sendMessage(String outgoing) {
LoRa.beginPacket(); // start packet
LoRa.write(destination); // add destination address
LoRa.write(localAddress); // add sender address
LoRa.write(msgCount); // add message ID
LoRa.write(outgoing.length()); // add payload length
LoRa.print(outgoing); // add payload
LoRa.endPacket(); // finish packet and send it
msgCount++; // increment message ID
}
void loop() {
if (millis() - lastSendTime > interval) {
String message = "HeLoRa!";
sendMessage(message);
Serial.println("Sending " + message);
lastSendTime = millis();
display.clear();
display.drawString(0, 0, String(lastSendTime));
display.display();
}
}
I also tried to set the values after LoRa.begin(), but then nothing is received by the receiver.
NOTE: It can't be the board itself, since I have several and have tried it with each one.