Открыть txt, внести изменения сохранить и выйти (firebird)

procedure TForm2.Button3Click(Sender: TObject);
  var Fname:string;
begin
if OpenDialog1.execute then
begin
Fname:=OpenDialog1.filename+'';
Memo1.lines.LoadFromFile(fname);
end;
end;
 
procedure TForm2.Button4Click(Sender: TObject);
begin
 SaveDialog1.FileName:=Fname;
 if SaveDialog1.Execute
 Then
Fname:=OpenDialog1.FileName;
Memo1.Lines.SaveToFile(FName);
  end;
end;

procedure TForm6.Button1Click(Sender: TObject);
var Fname:string;
begin
if OpenDialog1.Execute then
begin
Fname:=OpenDialog1.Filename+'';
Memo1.lines.LoadFromFile(fname);
end;
end;
 
procedure TForm6.Button2Click(Sender: TObject);
begin
  if SaveDialog1.Execute then
  begin
  Memo1.Lines.SaveToFile(OpenDialog1.FileName);
  end;
end;

procedure TfrmMainForm.Button2Click(Sender: TObject);
var fName: string;
begin
  with TSaveDialog.Create(nil) do try
    if not Execute then Exit;
    Memo1.Lines.SaveToFile(FileName);
  finally
    Free;
  end;
end;

procedure TForm6.Button2Click(Sender: TObject);
begin
  if not SaveDialog1.Execute then 
    Exit;
  Memo1.Lines.SaveToFile(SaveDialog1.FileName);
end;