Сохранение настроек програми

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using WindowsFormsApplication2.Properties;
 
namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
bool button = false;
        private void button1_Click(object sender, EventArgs e)
        {
          StreamWriter file = File.CreateText("Data\\file.txt");
          file.WriteLine(richTextBox1.Text);
          file.Close();
          Settings.Default["OnOff"] = button2.Text;
          button = !button;
          if (button)
          {
              button2.Text = "On";
          }
          else button2.Text = "Off";
        }
 
        private void Form1_Load(object sender, EventArgs e)
        {
            DirectoryInfo d = new DirectoryInfo("Data");
            d.Create();
            string file = File.ReadAllText("Data\\file.txt");
            richTextBox1.Text = file;
            button2.Text = Settings.Default["OnOff"].ToString();
        }
    }
}

           DirectoryInfo d = new DirectoryInfo(Application.StartupPath +"\\Data");
            if(!d.Exists) d.Create();
.....................................................................
            string file = File.ReadAllText(Application.StartupPath + "\\Data\\file.txt");
 
......................................................................
 
           StreamWriter file = File.CreateText(Application.StartupPath + "\\Data\\file.txt");