DataTable not saving changes back to DataGridView

Hello. I made a webforms app which shows a datagridview with all users recorded into the database. Everything works fine, except saving the data from dataTable to DataGridView. The dataTable is used just to search entries by a column name, which works fine as well. 
For example, if I'm entering into the database from the program, I can add any much data I want, and it is saved.
If I'm altering the database  (adding/changing/deleting data) after making a search, it don't save anymore.
Hers is my code for loading and how the dataTable selects data:

private void Form2_Load(object sender, EventArgs e)
        {
         this.tableTableAdapter.Fill(this.dbITPDataSet.Table);
        }

string connectionString = @"Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\dbITP.mdf;Integrated Security=True;Connect Timeout=30";
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                if (comboBox1.Text == "User")
                {
                    SqlDataAdapter sda = new SqlDataAdapter("select * FROM [Users] WHERE (User LIKE '" + textBox1.Text + "%')", connection);
                    DataTable dt = new DataTable();
                    sda.Fill(dt);
                    tableDataGridView.DataSource = dt;
                }

I've uploaded just a part of the code, all conditions are the same, just the field changes.

To save the data on the dataGridView, I used this event:

private void Form2_FormClosed(object sender, FormClosedEventArgs e)
        {
            tableAdapterManager.UpdateAll(dbITPDataSet);
        }

Do you have any ideas? I should pass somehow only changed data to the dataGridView.