not able to update key in hashmap

package com.example.model;

import java.util.List;

public class Course {
  private String mName;
  private List<Video> mVideos; 

  public Course(String name, List<Video> videos) {
    mName = name;
    mVideos = videos;
  }

  public String getName() {
    return mName;
  }

  public List<Video> getVideos() {
    return mVideos;
  }

}

package com.example.model;

public class Video {
  private String mTitle;

  public Video(String title) {
    mTitle = title;
  }

  public String getTitle() {
    return mTitle;
  }

  public void setTitle(String title) {
    mTitle = title;
  }

}

import com.example.model.Course;
import com.example.model.Video;

import java.util.Map;
import java.util.HashMap;
import java.util.List;
import java.util.Iterator;
import java.util.Map.Entry;

public class QuickFix {

  public void addForgottenVideo(Course course) {
    // TODO(1):  Create a new video called "The Beginning Bits"
    Video vd = new Video("The Beginning Bits");

    // TODO(2):  Add the newly created video to the course videos as the second video.
    course.getVideos().add(1,vd);

  }

  public void fixVideoTitle(Course course, String oldTitle, String newTitle) {
    Map<String,Video> map = new HashMap<String,Video>();
  map =videosByTitle(course);
    Iterator it = map.entrySet().iterator();
    Video vd = null;
    while(it.hasNext()){
      Entry item =(Entry) it.next();
      if(item.getKey().equals(oldTitle) ){
        vd =(Video) item.getValue();
       it.remove(); 
      }
    }

     map.put(newTitle,vd);



  }

  public Map<String, Video> videosByTitle(Course course) {
    Map<String,Video> map = new HashMap<String,Video>();
     List<Video> videoList = course.getVideos();
    String title = null;
    for(Video vd : videoList){
      title = vd.getTitle();
      map.put(title,vd);
    }

    return map;
  }

}