Having a few issues with my app.js code. Some items stay where they are even after checking their checkbox?

//Problem: No user interaction produces the desired results
//Solution: Add interactivity so the user can manage daily tasks

var taskInput = document.getElementById("new-task"); //new-task
var addButton = document.getElementsByTagName("button")[0]; //new-button
var incompleteTasksHolder = document.getElementById("incomplete-tasks"); //incomplete tasks
var completedTasksHolder = document.getElementById("completed-tasks"); //completed tasks

//New task list item
var createNewTaskElement = function(taskString) {
  //Create list item
  var listItem = document.createElement("li");
  //input (checkbox)
  var checkBox = document.createElement("input"); //checkbox
  //label
  var label = document.createElement("label"); //label
  //input (text)
  var editInput = document.createElement("input"); // text
  //button.edit
  var buttonEdit = document.createElement("button"); 
  //button.delete
  var buttonDelete = document.createElement("button"); 

  //Each element, needs to be modified 
  checkBox.type = "checkbox";
  editInput.type = "text";
  buttonEdit.innerText = "Edit";
  buttonEdit.className = "edit";
  buttonDelete.innerText = "Delete";
  buttonDelete.className = "delete";

  label.innerText = taskString;

  //Each element needs appending
  listItem.appendChild(checkBox);
  listItem.appendChild(label);
  listItem.appendChild(editInput);
  listItem.appendChild(buttonEdit);
  listItem.appendChild(buttonDelete);
  return listItem;
}

//Add a new task
var addTask = function() {
  console.log("Add task...");
  //Create a new list item with the text from the #new-task:
  var listItem = createNewTaskElement(taskInput.value);

  //Append listItem to incompleteTasksHolder
  incompleteTasksHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskCompleted);

  taskInput.value = "";
}

//Edit an existing task
var editTask = function() {
  console.log("Edit task...")

  var listItem = this.parentNode;

  var editInput = listItem.querySelector("input[type=text]");
  var label = listItem.querySelector("label");
  var containsClass = listItem.classList.contains("editMode")
  //if the class of the parent is .editMode
  if (containsClass) {
    //Switch from .editMode
    //label text becomes the input's value
    label.innerText = editInput.value;

  } else {
    //Switch to editMode
    //input value becomes to the label text
    editInput.value = label.innerText;
  }

  //Toggle .editMode on listItem
  listItem.classList.toggle("editMode");
}

//Mark a task as complete
var taskCompleted = function() {
  console.log("Complete task...")
    //Append the task list item to the #completed-tasks
  var listItem = this.parentNode;
  completedTasksHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskCompleted);
}

//Mark a task as incomplete
var taskIncomplete = function() {
  console.log("Incomplete task...")
  //When the checkbox is unchecked
    //Append the task list item to the #incomplete-tasts
  var listItem = this.parentNode;
  incompleteTasksHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskIncomplete);
}

//Delete an existing task
var deleteTask = function() {
  console.log("Delete task...")

  var listItem = this.parentNode;
  var ul = listItem.parentNode;

  //Remove the parent list item from the ul
  ul.removeChild(listItem);
}

//taskListItem = li of ul's 
var bindTaskEvents = function(taskListItem, checkBoxEventHandler) {
  console.log("Bind list item...")
  //select list item's children
  var checkBox = taskListItem.querySelector("input[type=checkbox]");
  var editButton = taskListItem.querySelector("button.edit");
  var deleteButton = taskListItem.querySelector("button.delete");

  //bind editTask to edit button
  editButton.onclick = editTask;

  //bind deleteTask to delete button
  deleteButton.onclick = deleteTask;

  //bind checkBoxEventHandler to checkbox
  checkBox.onchange = checkBoxEventHandler;
}

//Set the click handler to the addTask function
addButton.onclick = addTask;

var ajaxRequest = function() {
  console.log("AJAX request");
}
addButton.onclick = ajaxRequest;
addButton.addEventListener("click", addTask);
addButton.addEventListener("click", ajaxRequest);

//cycle over incompleteTasksHolder ul list items
for(var i = 0; i < incompleteTasksHolder.children.length; i++) {
  //for each list item
  //bind events to list item's children (taskCompleted)
   bindTaskEvents(incompleteTasksHolder.children[i], taskCompleted);
}

//cycle over completeTasksHolder ul list items
for(var x = 0; x < completedTasksHolder.children.length; x++) {
  //bind events to list item's children (taskIncomplete)
  bindTaskEvents(completedTasksHolder.children[x], taskIncomplete); 
}