Sir can you help me figure out the problem in displaying all the complex numbers here is my new code

Code:
//This program prints the initialized value of two complex numbers and allows
//the user to change the values of the real and imaginary numbers of the two
//complex numbers. This program can also solve the sum and the product of the
//two complex numbers and display all the complex numbers in the program.

#include<stdio.h>  
#include <conio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>

typedef struct CN{
  double cxr,cyr,czr;
  double cxi,cyi,czi;
  }CN;

CN Sum(CN CN1){
  CN1.czr=CN1.cxr+CN1.cyr;
  CN1.czi=CN1.cxi+CN1.cyi;
  return CN1;
  }
CN Mul(CN CN1){
  double a,b,c,d;
  a=CN1.cxr*CN1.cyr;
  b=CN1.cxr*CN1.cyi;
  c=CN1.cxi*CN1.cyr;
  d=-1.0*(CN1.cxi*CN1.cyi);
  CN1.czr=a+d;
  CN1.czi=b+c;
  return CN1;
  }

void DisplayCN(CN *p);

int main(void){
  CN *ptr,CN1,cz;
  ptr=&CN1;
  char error[128];
  int selection;

  ptr->cxr=1.0;
  ptr->cxi=-2.0;
  ptr->cyr=3.0;
  ptr->cyi=4.0;

  do{
    system("cls");
    printf("The Starting Values:\n");
    printf("CN1: %.2f%+.2fi\n",ptr->cxr,ptr->cxi);
    printf("CN2: %.2f%+.2fi\n\n",ptr->cyr,ptr->cyi);
    printf("Complex Number Selection Screen\n\n");
    printf("First Complex Number:\n");
    printf("1 - Change the Value of the Real Number\n");
    printf("2 - Change the Value of the Imaginary Number\n\n");
    printf("Second Complex Number:\n");
    printf("3 - Change the Value of the Real Number\n");
    printf("4 - Change the Value of the Imaginary Number\n\n");
    printf("Complex Number Operations:\n");
    printf("5 - Add the two Complex Numbers\n");
    printf("6 - Multiply the two Complex Numbers\n");
    printf("7 - Display all the Complex Numbers\n");
    printf("8 - Exit\n");
    fgets(error,128,stdin);
    selection=atoi(error);
    switch(selection){
      case 1:
        system("cls");
        printf("Change the Value of the Real Number\n");
        printf("CN1: %.2f%+.2fi\n",ptr->cxr,ptr->cxi);
        printf("New Value for the Real Number: ");
        scanf("%lf",&CN1.cxr);
        getchar();
        getche();
        break;
      case 2:
        system("cls");
        printf("Change the Value of the Imaginary Number\n");
        printf("CN1: %.2f%+.2fi\n",ptr->cxr,ptr->cxi);
        printf("New Value for the Imaginary Number: ");
        scanf("%lf",&CN1.cxi);
        getchar();
        getche();
        break;
      case 3:
        system("cls");
        printf("Change the Value of the Real Number\n");
        printf("CN2: %.2f%+.2fi\n",ptr->cyr,ptr->cyi);
        printf("New Value for the Real Number: ");
        scanf("%lf",&CN1.cyr);
        getchar();
        getche();
        break;
      case 4:
        system("cls");
        printf("Change the Value of the Imaginary Number\n");
        printf("CN2: %.2f%+.2fi\n",ptr->cyr,ptr->cyi);
        printf("New Value for the Imaginary Number: ");
        scanf("%lf",&CN1.cyi);
        getchar();
        getche();
        break;
      case 5:
        system("cls");
        printf("Sum of the Complex Numbers\n");
        cz=Sum(CN1);
        printf("The Sum of the Complex Numbers is %.2f%+.2fi\n",CN1.czr,CN1.czi);
        getche();
        break;
      case 6:
        system("cls");
        printf("Product of the Complex Numbers\n");
        CN1=Mul(CN1);
        printf("The Product of the Complex Numbers is %.2f%+.2fi\n",CN1.czr,CN1.czi);
        getche();
        break;
      case 7:
        system("cls");
        DisplayCN(ptr);
        break;
      case 8:
        exit(1);
        break;
      default:
        system("cls");
        printf("Invalid input. Please try again!!!\n");
        printf("Please press the spacebar to continue!!");
        getche();
        break;
    }
  }while(selection!=8);
}

void DisplayCN(CN *p){
  CN CN1;
  printf("The Values of the Complex Numbers:\n");
  printf("CN1: %.2f%+.2fi\n",p->cxr,p->cxi);
  printf("CN2: %.2f%+.2fi\n\n",p->cyr,p->cyi);
  printf("Sum of the Complex Numbers\n");
  CN1=Sum(CN1);
  printf("%.2f%+.2fi\n\n",CN1.czr,CN1.czi);
  printf("Product of the Complex Numbers\n");
  CN1=Mul(CN1);
  printf("%.2f%+.2fi\n",CN1.czr,CN1.czi);
  getche();
  }