how to change picture in picture box for all movies ?

this is my code :

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.Data.SqlClient;

namespace Film
{
public partial class MovieLib : Form
{
string SqlStr;
SqlCommand SqlCmd;
SqlDataAdapter SqlDa;
SqlDataReader SqlDr;

public MovieLib()
{
InitializeComponent();
}

public void Clear()
{
TxtName.Text = "";
TxtDirector.Text = "";
TxtYear.Text = "";
TxtType.Text = "";
}

private static SqlConnection CreateConnection()
{
return new SqlConnection("Data Source=(local);Initial Catalog=Movies;Integrated Security=True");
}

private void BtnAdd_Click(object sender, EventArgs e)
{
using (SqlConnection connection = CreateConnection())
using (SqlCommand command = new SqlCommand("Insert into Movies([Name], [Director], [Year], [Type]) VALUES (@Name, @Director, @Year, @Type)", connection))
{
command.Parameters.AddWithValue("@Name", TxtName.Text);
command.Parameters.AddWithValue("@Director", TxtDirector.Text);
command.Parameters.AddWithValue("@Year", TxtYear.Text);
command.Parameters.AddWithValue("@Type", TxtType.Text);

try
{
connection.Open();
command.ExecuteNonQuery();

MessageBox.Show("Inserted successfully.");
Clear();
}
catch (SqlException ex)
{
MessageBox.Show(ex.Message);
// TODO: Log the error somewhere
}
}
}

private void BtnEdit_Click(object sender, EventArgs e)
{
using (SqlConnection connection = CreateConnection())
using (SqlCommand command = new SqlCommand("UPDATE Movies SET Name = @Name, Director = @Director, Year = @Year, Type = @Type WHERE Id_Movies = @id", connection))
{
command.Parameters.AddWithValue("@Name", TxtName.Text);
command.Parameters.AddWithValue("@Director", TxtDirector.Text);
command.Parameters.AddWithValue("@Year", TxtYear.Text);
command.Parameters.AddWithValue("@Type", TxtType.Text);
command.Parameters.AddWithValue("@Id", TxtId.Text);

try
{
connection.Open();
command.ExecuteNonQuery();

MessageBox.Show("Edited successfully.");
Clear();
}
catch (SqlException ex)
{
MessageBox.Show(ex.Message);
// TODO: Log the error somewhere
}
}
}

private void TxtSearch_Click(object sender, EventArgs e)
{

using (SqlConnection connection = CreateConnection())
using (SqlCommand command = new SqlCommand("SELECT Name, Director, Year, Type FROM Movies WHERE Id_Movies = @id", connection))
{
command.Parameters.AddWithValue("@Id", TxtId.Text);

try
{
connection.Open();

using (SqlDataReader reader = command.ExecuteReader(CommandBehavior.CloseConnection))
{
if (!reader.Read())
{
MessageBox.Show("Movie not found.");
}
else
{
TxtName.Text = (string)reader["Name"];
TxtDirector.Text = (string)reader["Director"];
TxtYear.Tex