delphi 更改系统时间方式

unit Unit1; 
 
interface 
 
uses 
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, 
  StdCtrls, ComCtrls; 
 
type 
  TForm1 = class(TForm) 
    Button1: TButton; 
    Button2: TButton; 
    Button3: TButton; 
    Button4: TButton; 
    Edit1: TEdit; 
    Edit2: TEdit; 
    Edit3: TEdit; 
    Label1: TLabel; 
    Label2: TLabel; 
    Label3: TLabel; 
    Label4: TLabel; 
    Label5: TLabel; 
    Label6: TLabel; 
    Button5: TButton; 
    procedure Button1Click(Sender: TObject); 
    procedure SetSysDateFormat(s: string); 
    function GetsysShortDateFormat: string; 
    function GetsysLongDateFormat: string; 
    function GetsysTimeFormat: string; 
    procedure Button2Click(Sender: TObject);