Dim frm1 As New Form1
'On Error Resume Next

frm4.TextBox1.Text = Me.TextBox1.Text
frm4.TextBox2.Text = Me.TextBox2.Text
frm4.TextBox3.Text = Me.TextBox3.Text
frm4.TextBox4.Text = Me.TextBox4.Text
frm4.TextBox5.Text = Me.TextBox5.Text
frm4.TextBox6.Text = Me.TextBox6.Text
frm4.TextBox7.Text = Me.TextBox7.Text
frm4.lb8.Text = Me.TextBox1.Text
frm4.Show()

Try
Dim n As String = lb8.Text
Dim updateinto As New OleDb.OleDbCommand
Dim constre As String = "Provider=Microsoft.Jet.OLEDB.4.0; Data source =" & Application.StartupPath & "\ecole.mdb"

Dim conn As New OleDbConnection(constre)
updateinto.Connection = conn
updateinto.CommandType = CommandType.Text
updateinto.CommandText = "UPDATE enfant SET num = '" & Trim(TextBox1.Text) & "' ,nom = '" & Trim(TextBox2.Text) & "' ,prenom = '" & Trim(TextBox3.Text) & "' ,datedenaissance = '" & Trim(TextBox4.Text) & "' ,classep = '" & Trim(TextBox5.Text) & "' ,classeamcf = '" & Trim(TextBox6.Text) & "' ,photo = '" & Trim(TextBox7.Text) & "' where num ='" & Trim(TextBox1.Text) & "'"
conn.Open()
updateinto.ExecuteNonQuery()
conn.Close()
MsgBox(" bien modifier")
Catch ex As Exception
'Exit Sub
End Try
Me.Close()
frm1.Show()