#include <Servo.h>
    Servo servo1;
    int previousangle1;
    int dc; 
    void setup()
      {
        dc = 10;    // Delay calibration 
        servo1.attach(11);  // connect Servo to pin 11
        pinMode(A0, INPUT); // Connect potentiometer or Joystick x or y pin to A0 input
        previousangle1 = 90; // Initialize position to 90 degrees (180 degree servo)
      }
    
    void loop()
      {     
           
      int val1 = analogRead(A0); // Read the potentiometer position
      int angle1 = map(val1, 0, 1023, 0, 180); // Map the value to be used with servo
    
      if(angle1>previousangle1)
      {
        for(int i=previousangle1; i<=angle1; i++)
        {
          servo1.write(i); //turn servo by 1 degrees
          delay(dc);        //delay for smoothness
        }
      }
      // Fix: This needed to be an else if 
      // Original piece of code had it as a second stand alone if
      else if(angle1<previousangle1)
      {
        for(int j=previousangle1; j>=angle1; j--)
        {
          servo1.write(j); 
          delay(dc);        
        }
      }
      delay(dc);  
      previousangle1 = angle1; 
      }

What you need to do now, is make similar code, with different variables for all 4 servos. I still have to check the addition of a capacitor to make it work even better and maybe some ferrite filters to eliminate noise.

Original code is taken from here: https://arduino.stackexchange.com/a/29970/76974

I will edit this, adding code for the rest of the servos later on.

  #include <Servo.h>
    Servo servo1;
    int previousangle1;
    int dc; 
    void setup()
      {
        dc = 10;    // Delay calibration 
        servo1.attach(11);  // connect Servo to pin 11
        pinMode(A0, INPUT); // Connect potentiometer or Joystick x or y pin to A0 input
        previousangle1 = 90; // Initialize position to 90 degrees (180 degree servo)
      }
    
    void loop()
      {     
           
      int val1 = analogRead(A0); // Read the potentiometer position
      int angle1 = map(val1, 0, 1023, 0, 180); // Map the value to be used with servo
    
      if(angle1>previousangle1)
      {
        for(int i=previousangle1; i<=angle1; i++)
        {
          servo1.write(i); //turn servo by 1 degrees
          delay(dc);        //delay for smoothness
        }
      }
      // Fix: This needed to be an else if 
      // Original piece of code had it as a second stand alone if
      else if(angle1<previousangle1)
      {
        for(int j=previousangle1; j>=angle1; j--)
        {
          servo1.write(j); 
          delay(dc);        
        }
      }
      delay(dc);  
      previousangle1 = angle1; 
      }

What you need to do now, is make similar code, with different variables for all 4 servos. I still have to check the addition of a capacitor to make it work even better.

Original code is taken from here: https://arduino.stackexchange.com/a/29970/76974

I will edit this, adding code for the rest of the servos later on.