Textbox event for autocomplete for gridview in winform

I've been looking online for the correct event to use for a textbox to auto-generate suggestions like google.com so I don't have to type the whole cell value to find what I'm looking for. Currently, I have a button where when clicked it will filter the grid to what I ask for, but not just using the textbox to filter. I know there's Keypress, textchanged, etc. and I tried the different events to see if the datagridview filters as I type. No success. The key press event doesn't filter as I type. The textchanged event won't let me type in the textbox. So how can I accomplish this?

Code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SampleARDUserGroup
{
    public partial class FirstPage : Form
    {
        SqlConnection con;
        SqlDataAdapter adap;
        DataSet ds;
        SqlCommandBuilder cmbl;
        public FirstPage()
        {
            InitializeComponent();
        }

        private void FirstPage_Load(object sender, EventArgs e)
        {


            try
            {
                con = new SqlConnection();
                con.ConnectionString = "My Data Source";
                con.Open();
                adap = new SqlDataAdapter("select RowID as 'ID',UserID as 'User ID', FirstName as 'First Name', LastName as 'Last Name', email as 'E-mail' from JoshTestTable", con);
                ds = new System.Data.DataSet();
                adap.Fill(ds, "User_Details");
                DGV1.DataSource = ds.Tables[0];
                DGV1.Columns[0].Visible = false;
                DGV1.Columns[2].Visible = false;
                DGV1.Columns[3].Visible = false;
                DGV1.Columns[4].Visible = false;
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error\n" + ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void btnSearch_Click(object sender, EventArgs e)
        {
            con = new SqlConnection();
            con.ConnectionString = "My Data Source";
            SqlDataAdapter sda = new SqlDataAdapter("Select UserID,FirstName,LastName,Email FROM JoshTestTable where UserID like '%" + txtSearch.Text.Trim() + "%' OR FirstName like '%" + txtSearch.Text.Trim() + "%' OR FirstName like '%" + txtSearch.Text.Trim() + "%' OR LastName like '%" + txtSearch.Text.Trim() + "%' OR Email like '%" + txtSearch.Text.Trim() + "%'", con);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            DGV1.DataSource = dt;
            DGV1.Columns[1].Visible = false;
            DGV1.Columns[2].Visible = false;
            DGV1.Columns[3].Visible = false;

        }

        private void linkLabel3_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
            AddDeleteUsers f2 = new AddDeleteUsers();
            f2.ShowDialog(); 
        }

        private void AddUsersToGroupsLink_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
            AddUsersToGroups f3 = new AddUsersToGroups();
            f3.ShowDialog(); 
        }

        private void AddGroupsToUsersLink_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
            AddGroupsToUsers f4 = new AddGroupsToUsers();
            f4.ShowDialog(); 
        }

        private void txtSearch_TextChanged(object sender, EventArgs e)
        {
            AutoCompleteStringCollection namesCollection = new AutoCompleteStringCollection();

            SqlConnection con = new SqlConnection();
            con.ConnectionString = "My Data Source";
            con.Open();
            String query = "select UserID from JoshTestTable  where UserID like '%" + txtSearch.Text + "%'";
            SqlCommand cmd = new SqlCommand(query, con);
            SqlDataReader rr = cmd.ExecuteReader();
            rr.Read();
            while (rr.Read())
                namesCollection.Add(rr["UserID"].ToString());
            rr.Close();
            txtSearch.AutoCompleteMode = AutoCompleteMode.Suggest;
            txtSearch.AutoCompleteSource = AutoCompleteSource.CustomSource;
            txtSearch.AutoCompleteCustomSource = namesCollection;
        }      
    }
}