i was searching since a few days and finally after posting i found the solution

so i give you the code

On Error Resume Next
Const wdAutoRecoverPath = 5
Const wdBorderArtPath = 19
Const wdCurrentFolderPath = 14
Const wdDocumentsPath = 0
Const wdGraphicsFiltersPath = 10
Const wdPicturesPath = 1
Const wdProgramsPath = 9
Const wdProofingToolsPath = 12
Const wdStartupPath = 8
Const wdStyleGalleryPath = 15
Const wdTempFilesPath = 13
Const wdTextConvertersPath = 11
Const wdToolsPath = 6
Const wdTutorialPath = 7
Const wdUserOptionsPath = 4
Const wdUserTemplatesPath = 2
Const wdWorkgroupTemplatesPath = 3

Set objWord = CreateObject("Word.Application")
Set objOptions = objWord.Options
objOptions.DefaultFilePath(wdUserTemplatesPath) = "C:\testmodele3"
msgbox ("opération terminées")
objWord.Quit