How do you define pitch yaw for quadcopter with Multiwii?

Question

I have a problem defining pitch and yaw for my quadcopter. Every time I set my PWM for my yaw to 1500, it's not affecting my yaw, but instead it's affecting my roll. I did not even do anything to my roll, and the PWM value of my roll is locked to 1500.

#include

#define pinA  10
#define pinB  11
#define THR_PIN 5
#define ROLL_PIN 0   //pin 1 receiver
#define PITCH_PIN 1  //pin 2 receiver

int pitch, roll, pitchpwm, rollpwm, error_x, last_error_x;
float pid;
int g_dt = 1;
float kp = 1.0;
float ki = 0.0;
float kd = 0.0;

String dataIn = "";
String data[3];
bool parsing;

Servo outpwm1;
Servo outpwm2;

int dataA;
int pwmA;
int pwmB;

int pwm_value = 0;
volatile int prev_time = 0;
volatile int roll_value = 0;
volatile int prev_time1 = 0;
volatile int pitch_value = 0;
volatile int prev_time2 = 0;

uint32_t count;

void setup() {
  Serial.begin(115200);
  Serial.println("connected!");
  parsing = false;
  init_remote();
  Serial.print("MODE");
  Serial.print(',');
  Serial.print("PWM Pitch");
  Serial.print(',');
  Serial.print("PWM Roll");
  Serial.print(',');
  Serial.print("Koordinat y");
  Serial.print(',');
  Serial.print("Koordinat x");
  Serial.print(',');
  Serial.print("pitchpwm");
  Serial.print(',');
  Serial.println("nilai PID");
  outpwm1.attach(pinA);
  outpwm2.attach(pinB);
}

outpwm1.writeMicroseconds(pwmA);
outpwm2.writeMicroseconds(pwmB);
outpwm2.writeMicroseconds(pitch_value);

}

My goal is to control the value of my pitch and yaw. Can anyone tell me where I'm wrong? Thank you so much.