Option Explicit
Private Declare Function GetDeviceCaps Lib "gdi32" (ByVal hdc As Long, ByVal nIndex As Long) As Long
Private Declare Function ChangeDisplaySettings Lib "user32" Alias "ChangeDisplaySettingsA" (lpDevMode As Any, ByVal dwflags As Long) As Long
Private Const CCDEVICENAME As Long = 32
Private Const CCFORMNAME As Long = 32
Private Const DM_BITSPERPEL As Long = &H40000
Private Const DM_PELSWIDTH As Long = &H80000
Private Const DM_PELSHEIGHT As Long = &H100000
Private Const DM_DISPLAYFLAGS As Long = &H200000
Private Const DM_DISPLAYFREQUENCY = &H400000
Private Const CDS_FORCE As Long = &H80000000
Private Const BITSPIXEL As Long = 12
Private Const HORZRES As Long = 8
Private Const VERTRES As Long = 10
Private Const VREFRESH = 116
Private Type DEVMODE
   dmDeviceName      As String * CCDEVICENAME
   dmSpecVersion     As Integer
   dmDriverVersion   As Integer
   dmSize            As Integer
   dmDriverExtra     As Integer
   dmFields          As Long
   dmOrientation     As Integer
   dmPaperSize       As Integer
   dmPaperLength     As Integer
   dmPaperWidth      As Integer
   dmScale           As Integer
   dmCopies          As Integer
   dmDefaultSource   As Integer
   dmPrintQuality    As Integer
   dmColor           As Integer
   dmDuplex          As Integer
   dmYResolution     As Integer
   dmTTOption        As Integer
   dmCollate         As Integer
   dmFormName        As String * CCFORMNAME
   dmUnusedPadding   As Integer
   dmBitsPerPel      As Integer
   dmPelsWidth       As Long
   dmPelsHeight      As Long
   dmDisplayFlags    As Long
   dmDisplayFrequency As Long
End Type
Private Sub Form_Load()
On Error Resume Next
Dim DM As DEVMODE
With DM
    .dmPelsWidth = 800
    .dmPelsHeight = 600
    .dmBitsPerPel = 16
    .dmDisplayFrequency = 60
    .dmFields = DM_PELSWIDTH Or DM_PELSHEIGHT Or DM_BITSPERPEL Or DM_DISPLAYFREQUENCY
    .dmSize = LenB(DM)
End With
If ChangeDisplaySettings(DM, CDS_FORCE) <> 0 Then
End
End If
End
End Sub