API функция для изменения разрешения экрана.

Public Const DM_BITSPERPEL = &H40000
Public Const DM_PELSWIDTH = &H80000
Public Const DM_PELSHEIGHT = &H100000
Public Const CCHDEVICENAME = 32
Public Const CCHFORMNAME = 32
Type DEVMODE
  dmDeviceName As String * CCHDEVICENAME
  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 * CCHFORMNAME
  dmUnusedPadding As Integer
  dmBitsPerPel As Integer
  dmPelsWidth As Long
  dmPelsHeight As Long
  dmDisplayFlags As Long
  dmDisplayFrequency As Long
End Type
 
Declare Function ChangeDisplaySettings Lib 'user32.dll' Alias 'ChangeDisplaySettingsA' (lpDevMode As DEVMODE, ByVal dwFalgs As Long) As Long
...
Public Sub SetVideoMode(Width As Long, height As Long, Depth As Long)
  Dim dm As DEVMODE
  dm.dmPelsWidth = Width
  dm.dmPelsHeight = height
  dm.dmBitsPerPel = Depth
  dm.dmSize = Len(dm)
  dm.dmFields = DM_PELSWIDTH + DM_PELSHEIGHT + DM_BITSPERPEL
  ChangeDisplaySettings dm, 0
End Sub