Title: Set resolution of screen
Use ChangeDispleySettings function with TDeviceModeA structure for this problem.
procedure TForm1.Button1Click(Sender: TObject);
var
MyMode: TDeviceModeA;
begin
MyMode.dmSize:=Sizeof(MyMode);
MyMode.dmFields:=DM_PELSWIDTH and DM_PELSWIDTH;
MyMode.dmPelsWidth:=StrToInt(Edit1.Text);
MyMode.dmPelsHeight:=StrToInt(Edit2.Text);
ChangeDisplaySettings(MyMode, 0);
end;