When loading the txt file I get all the songs but when I quit and start the Karaoke.java again it keeps only #1 song

import com.teamtreehouse.KaraokeMachine;
import com.teamtreehouse.model.SongBook;
import com.teamtreehouse.model.SongBook;
import com.teamtreehouse.model.SongBook;

public class Karaoke {

  public static void main(String[] args) {
    SongBook songBook = new SongBook();
    songBook.importFrom("songs.txt");
    KaraokeMachine machine = new KaraokeMachine(songBook);
    machine.run();
    System.out.println("Saving book....");
    songBook.exportTo("songs.txt");
  }
}

package com.teamtreehouse.model;

import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.HashMap;
import java.util.TreeMap;
import java.util.Comparator;
import java.util.Map;


public class SongBook {
  private List<Song> mSongs;

  public SongBook() {
    mSongs = new ArrayList<Song>();
  }


  public void exportTo(String fileName) {


    try (
            FileOutputStream fos = new FileOutputStream(fileName);
            PrintWriter writer = new PrintWriter(fos);

        ) {
              for (Song song: mSongs) {

                writer.printf("%s|%s|%s",
                              song.getArtist(),
                              song.getTitle(),
                              song.getVideoUrl());

              }

          } catch(IOException ioe) {

            System.out.printf("Problem with saving %s %n", fileName);
            ioe.printStackTrace();
          }
    }


    public void importFrom(String fileName) {


          try (

                FileInputStream fis = new FileInputStream(fileName);
                BufferedReader reader = new BufferedReader(new InputStreamReader(fis));
          ) {

            String line;
            while ((line = reader.readLine()) != null ) {

              String[] args = line.split("\\|");

              addSong(new Song(args[0],args[1],args[2]));

            }

          } catch (IOException ioe) {

            System.out.printf("There was a problem loading %s %n", fileName);
            ioe.printStackTrace();

          }


    }

  public void addSong(Song song) {
    mSongs.add(song);
  }

  public int getSongCount() {
    return mSongs.size();
  }
  //FIX ME this should be cached
  private Map<String,List<Song>> byArtist() {

    Map<String,List<Song>> byArtist = new TreeMap<>();

    for (Song song : mSongs) {

     List<Song> artistSongs = byArtist.get(song.getArtist());

      if (artistSongs == null) {

        artistSongs = new ArrayList<>();
        byArtist.put(song.getArtist(),artistSongs);

      }

        artistSongs.add(song);
    }
        return byArtist;


  }

    public Set<String> getArtists() {

      return byArtist().keySet();


    }

    public List<Song> getSongsForArtist(String artistName) {

      List<Song> songs = byArtist().get(artistName);

      songs.sort(new Comparator<Song>() {
      @Override
      public int compare(Song song1, Song song2) {

        if (song1 == song2) {
          return 0;
        }
          return song1.mTitle.compareTo(song2.mTitle);

      }

      });
        return songs;        
    }
}