public partial class DataWrite : Form
    {
        DataSet Ds;
        BindingSource bSourceTxtBoxes = new BindingSource();
        ...

private void DataWrite_Load(object sender, EventArgs e)
        {
            String tblName = tablesBox.Text;
            
            //TextBoxes BindingSources
            bSourceTxtBoxes.DataSource = Ds.Tables[tblName];            

            //Bindings for TextBoxes
            Binding TxtBox1Bind = new Binding("Text", bSourceTxtBoxes, GetColumnName(0, tblName));
            Binding TxtBox2Bind = new Binding("Text", bSourceTxtBoxes, GetColumnName(1, tblName));
            Binding TxtBox3Bind = new Binding("Text", bSourceTxtBoxes, GetColumnName(2, tblName));
            Binding TxtBox4Bind = new Binding("Text", bSourceTxtBoxes, GetColumnName(3, tblName));
            textBox1.DataBindings.Add(TxtBox1Bind);
            textBox2.DataBindings.Add(TxtBox2Bind);
            textBox3.DataBindings.Add(TxtBox3Bind);
            textBox4.DataBindings.Add(TxtBox4Bind);
            ...

private String GetColumnName(int colNum, string tblName)
        {
            return Ds.Tables[tblName].Columns[colNum].ColumnName;
        }

private void tablesBox_SelectedIndexChanged(object sender, EventArgs e)
        {
            String tblName = tablesBox.Text;
            
            //Change TextBoxes BindingSources
            bSourceTxtBoxes.DataSource = Ds.Tables[tblName];
            
        }