My servo does not hold position with arduino

/*
 * Created by ArduinoGetStarted.com
 *
 * This example code is in the public domain
 *
 * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-joystick-servo-motor
 */

#include <Servo.h>

#define VRX_PIN1     A0 // Arduino pin connected to VRX pin for the first joystick
#define VRY_PIN1     A1 // Arduino pin connected to VRY pin for the first joystick
#define SERVO_X1_PIN 2  // Arduino pin connected to Servo motor 1 for the first pair
#define SERVO_Y1_PIN 3  // Arduino pin connected to Servo motor 2 for the first pair

#define VRX_PIN2     A2 // Arduino pin connected to VRX pin for the second joystick
#define VRY_PIN2     A3 // Arduino pin connected to VRY pin for the second joystick
#define SERVO_X2_PIN 4  // Arduino pin connected to Servo motor 1 for the second pair
#define SERVO_Y2_PIN 5  // Arduino pin connected to Servo motor 2 for the second pair

Servo xServo1; // create servo object to control the first servo motor
Servo yServo1; // create servo object to control the second servo motor

Servo xServo2; // create servo object to control the third servo motor
Servo yServo2; // create servo object to control the fourth servo motor

void setup() {
  Serial.begin(9600);
  xServo1.attach(SERVO_X1_PIN);
  yServo1.attach(SERVO_Y1_PIN);
  xServo2.attach(SERVO_X2_PIN);
  yServo2.attach(SERVO_Y2_PIN);
}

void loop() {
  // read analog X and Y analog values for the first joystick
  int xValue1 = analogRead(VRX_PIN1);
  int yValue1 = analogRead(VRY_PIN1);

  // read analog X and Y analog values for the second joystick
  int xValue2 = analogRead(VRX_PIN2);
  int yValue2 = analogRead(VRY_PIN2);

  int xAngle1 = map(xValue1, 0, 1023, 0, 180); // scale it to the first servo's angle (0 to 180)
  int yAngle1 = map(yValue1, 0, 1023, 0, 180); // scale it to the second servo's angle (0 to 180)

  int xAngle2 = map(xValue2, 0, 1023, 0, 180); // scale it to the third servo's angle (0 to 180)
  int yAngle2 = map(yValue2, 0, 1023, 0, 180); // scale it to the fourth servo's angle (0 to 180)

  xServo1.write(xAngle1); // rotate first servo motor
  yServo1.write(yAngle1); // rotate second servo motor
  xServo2.write(xAngle2); // rotate third servo motor
  yServo2.write(yAngle2); // rotate fourth servo motor

  // print data to Serial Monitor on Arduino IDE
  Serial.print("Joystick 1: ");
  Serial.print(xValue1);
  Serial.print(", ");
  Serial.print(yValue1);
  Serial.print(" => Servo Motor 1: ");
  Serial.print(xAngle1);
  Serial.print("°, ");
  Serial.print(yAngle1);
  Serial.print("° - Joystick 2: ");
  Serial.print(xValue2);
  Serial.print(", ");
  Serial.print(yValue2);
  Serial.print(" => Servo Motor 2: ");
  Serial.print(xAngle2);
  Serial.print("°, ");
  Serial.print(yAngle2);
  Serial.println("°");
}