Declare Function SendNotifyMessageA Lib "user32" (ByVal hwnd As Long, ByVal msg As Long, _
                 ByVal wParam As Long, lParam As Any) As Long
Declare Function SetDefaultPrinterA Lib "winspool.drv" (ByVal pszPrinter As String) As Long

Const HWND_BROADCAST As Long = &HFFFF&
Const WM_WININICHANGE As Long = &H1A

Sub Test()
    SetDefaultPrinterA "PC1"
    Call SendNotifyMessageA(HWND_BROADCAST, WM_WININICHANGE, 0, ByVal "Windows")
End Sub