Textbox and cursor placement after TextChanged

I have a sub that seems to work fine but after I do txtwhatever = txtwhatever & "-" it works but it places the cursor in the front of the textbox again which of course messes up the number if you are typing it straight in.
How can I format the text ie: "111-222-333" while the number is being entered without having the cursor placed at the front of the textbox after each event.

   
Private Sub txtFullSocial_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtFullSocial.TextChanged
        If txtFullSocial.TextLength = 3 Then
            txtFullSocial.Text = txtFullSocial.Text & "-"
        ElseIf txtFullSocial.TextLength = 6 Then
            txtFullSocial.Text = txtFullSocial.Text & "-"
        Else
            Exit Sub
        End If
    End Sub