Make a 2D array in a struct, store strings inside array

Question

I have to make a library system using structs and pointers, that registers a person with their name, ID, phone number, and the name of the books (maximum 3). I have created a struct for every borrower, and I am trying to store input taken by the user, specifically at the part of getting the book titles, to store into an array of other structs (for other borrowers). I have to be able to free the locations of the borrowers once they return all books, so I'd have to use dynamic memory for that.

This is the code I have so far, not sure how exactly I would go about storing every borrower using pointers.

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define MAX_NAME_SZ 256
#define CLEAR() system("CLS")

struct borrower
{
    char name[20];
    char lastName[20];
    char id[7];
    char phoneNumber[10];
    char titleOfBook[3][20];
};

int main(void)
{
    struct borrower b;
    char op;

    do
    {
        puts("\n1) Register borrower");
        puts("2) Find by ID");
        puts("3) Show All");
        puts("4) Erase by ID");
        puts("0) Exit");
        printf("Option:");

        setbuf(stdin, 0);
        opc=getchar();

        switch(op)
        {
            case '1':
                RegisterBorrower(&b);
                break;

            case '2':
                //showID();
                break;

            case '3':
                //showAll();
                break;

            case '4':
                //erase();
                break;

            case '0':
                break;
        }
        }while (op!=48);

    return 0;

}

void RegisterBorrower(struct borrower *b)
{
    CLEAR();
    setbuf(stdin,0);
    printf("ID: "); gets(p->id);
    printf("Name: "); gets(p->name);
    printf("Last Name: "); gets(p->lastName);
    setbuf(stdin,0);
    printf("Phone Number: "); gets(p->phoneNumber);

    int numberOfBooks=0, cont=0, i;
    char bookTitle[20];
    printf("How many books do you want to take out?(max 3): ");
    scanf("%d", &numberOfBooks);
    setbuf(stdin,0);
    if(numberOfBooks<=3 && numberOfBooks>0)
    {
        for(i=0; i<numberOfBooks; i++)
        {
            setbuf(stdin,0);
            printf("Book Title: "); gets(bookTitle);
            strcpy(p->titleOfBook[i][0], bookTitle);
        }
    }else
    {
        printf("You cannot take out this amount of books.");
    }
}

Everything "works" (doesn't crash) up until the part I ask for the book titles, it only runs once. Any help would be greatly appreciated.

EDIT: My problem was that I used

strcpy(p->titleOfBook[i][0], bookTitle);

which only copies to one character because of the [0]. I changed it to

strcpy(p->titleOfBook[i], bookTitle);

and it worked fine.