Update cell value in Datagridview in C#

Question

Hello!

When clicking a button, I need you to update the value of a cell in the datagridview.

follows the code I tried but didn’t work.

  private void btnAcesso_Click(object sender, EventArgs e)
    {
        foreach (DataGridViewRow item in dgvLista.SelectedRows)
        {
            dgvLista.Rows[item.Index].Cells["acesso"].Value = "S";
        }
    }

You have to update from the selected line.

Note: Enter the foreach but does not update.

Thank you.

Grid completion:

 var source = new BindingSource();
            source.DataSource = lstMenuAux;
            dgvLista.DataSource = source;