Rails: Checkbox to change the value of a variable on click

I have a basic to do type app and I am trying to change the variable completed for an item to the current date/time when I click a checkbox. I found this post, which has led me to the following code structure:

My lists#show, on which items are created, checked off (updated), edited, and deleted:

<div class="container">
  <div class="row" style="height: 70px"></div>
</div>

<div class="col-xs-10 col-xs-push-1 container">
  <div class="md-well">
    <h1 class="text-center"><%= @list.name %></h1>
    <% if @items.count == 0 %>
      <h4 class="text-center">You don't have any items on this list yet! Want to add some?<h4>
    <% elsif @items.count == 1 %>
      <h4 class="text-center">Only <%= @items.count %> Item To Go!</h4>
    <% else %>
      <h4 class="text-center">You Have <%= @items.count %> Items To Go!</h4>
    <% end %>

    <%= render 'items/form' %>

    <% @items.each do |item|%>
      <p>
       <%= form_for [@list, item], class: "inline-block", id: 'item<%= item.id %>' do |f| %>
         <%= f.check_box :completed, :onclick => "$this.parent.submit()" %>
       <% end %>
        <%= item.name %>
        ( <%= link_to "Delete", list_item_path(@list, item), method: :delete %> )
      </p>
    <% end %>

    <div class="text-center">
      <%= link_to "Back to My Lists", lists_path %>
    </div> <!-- text-center -->

  </div> <!-- well -->
</div> <!-- container -->

Here is my update method in my items_controller (which I believe has jurisdiction instead of the lists_controller even though it is the lists#show page because it is an item being updated:

  def update
    @list = List.friendly.find(params[:list_id])
    @item = @list.items.find(params[:id])

    @item.name = params[:item][:name]
    @item.delegated_to = params[:item][:delegated_to]
    @item.days_til_expire = params[:item][:days_til_expire]
    @item.completed = params[:item][:completed]
    @item.user = current_user

    if @item.update_attributes(params[:item])
      @item.completed = Time.now
    end

    if @item.save
      flash[:notice] = "List was updated successfully."
      redirect_to @list
    else
      flash.now[:alert] = "Error saving list. Please try again."
      render :edit
    end
  end

Here is what is currently appearing:

And here are the two problems I'm having:

1. LESS IMPORTANT PROBLEM: The checkboxes should be displayed inline with the list items but aren't. My class inline-block simply makes links to this in the application.scss file:

   .inline-block { display: inline-block !important; }

2. MORE IMPORTANT PROBLEM: Even after the checkbox is clicked, the value for completed remains nil as per my console:

   [6] pry(main)> Item.where(name: "Feed Dexter") Item Load (0.1ms) SELECT "items".* FROM "items" WHERE "items"."name" = ? [["name", "Feed Dexter"]] => [#]

Any ideas how to make this functional?