Working with Arduino and CD74HC4067 MUX

These are the values i get when i have USB LED 1 ON:

    USB LED 1: 737
    USB LED 2: 711
    USB LED 1: 734
    USB LED 2: 710
    USB LED 1: 734
    USB LED 2: 710
    USB LED 1: 733
    USB LED 2: 709
    USB LED 1: 734
    USB LED 2: 709
    USB LED 1: 734
    USB LED 2: 710

These are the values I have with USB LED 1 OFF:

    USB LED 1: 736
    USB LED 2: 720
    USB LED 1: 734
    USB LED 2: 720
    USB LED 1: 734
    USB LED 2: 719
    USB LED 1: 734
    USB LED 2: 719
    USB LED 1: 734
    USB LED 2: 720
    USB LED 1: 734
    USB LED 2: 719
    USB LED 1: 733

These are the values when USB LED 2 ON:

    USB LED 1: 736
    USB LED 2: 719
    USB LED 1: 734
    USB LED 2: 719
    USB LED 1: 734
    USB LED 2: 720
    USB LED 1: 734
    USB LED 2: 720
    USB LED 1: 734
    USB LED 2: 718

And these are the values with USB LED 2 OFF:

    USB LED 1: 737
    USB LED 2: 710
    USB LED 1: 734
    USB LED 2: 710
    USB LED 1: 734
    USB LED 2: 710
    USB LED 1: 735
    USB LED 2: 710
    USB LED 1: 735
    USB LED 2: 711

Are you can see above, its a very SLIM margin when the LED is either on or off.
When LED 1 is ON its : from 733 to 734
When LED 1 is OFF its: from 734 to 736
When LED 2 is ON its : from 718 to 720
When LED 2 is OFF its: from 710 to 711
What I am hoping to get is a constant number instead of a random range so that I know for sure its either ON or OFF. 734 ON and also 734 for OFF does not cut it for trying to figure out if its on or off.

  //Mux control pins
    int s0 = 8;
    int s1 = 9;
    int s2 = 10;
    int s3 = 11;
    
    //Mux in "SIG" pin
    int SIG_pin = 0;
        
    void setup(){
      pinMode(s0, OUTPUT); 
      pinMode(s1, OUTPUT); 
      pinMode(s2, OUTPUT); 
      pinMode(s3, OUTPUT); 
    
      digitalWrite(s0, LOW);
      digitalWrite(s1, LOW);
      digitalWrite(s2, LOW);
      digitalWrite(s3, LOW);
    
      Serial.begin(9600);
    }
        
    void loop(){
        int val = readMux(1);
        Serial.print("USB LED 1: ");
        Serial.println(val);
        delay(1000);
        
        val = readMux(0);
        Serial.print("USB LED 2: ");
        Serial.println(val);
        delay(1000);
    }
        
    int readMux(int channel){
      int controlPin[] = {s0, s1, s2, s3};
    
      int muxChannel[16][4]={
        {0,0,0,0}, //channel 0
        {1,0,0,0}, //channel 1
        {0,1,0,0}, //channel 2
        {1,1,0,0}, //channel 3
        {0,0,1,0}, //channel 4
        {1,0,1,0}, //channel 5
        {0,1,1,0}, //channel 6
        {1,1,1,0}, //channel 7
        {0,0,0,1}, //channel 8
        {1,0,0,1}, //channel 9
        {0,1,0,1}, //channel 10
        {1,1,0,1}, //channel 11
        {0,0,1,1}, //channel 12
        {1,0,1,1}, //channel 13
        {0,1,1,1}, //channel 14
        {1,1,1,1}  //channel 15
      };
    
      //loop through the 4 sig
      for(int i = 0; i < 4; i ++){
        digitalWrite(controlPin[i], muxChannel[channel][i]);
      }
    
      //read the value at the SIG pin
      int val = analogRead(SIG_pin);
    
      //return the value
      return val;

What sensors are actually connected to the multiplexer? Have you verified that they give appropriate values when connected directly?

Yes each LED gives off ~3.3v when its on and 0v when off.

This is what i am basting my code on: HERE

Yes each LED gives off ~3.3v when its on and 0v when off.

Silly me. I thought LEDs gave off light.