Попробуйте .NumberFormat
:
Sub format_date()
Dim date_column As Range
With ActiveSheet
With .Cells
Set date_column = .Find(What:="date", LookIn:=xlFormulas, _
LookAt:=xlWhole, SearchOrder:=xlByRows, SearchDirection:=xlNext, _
MatchCase:=True, SearchFormat:=False)
End With
If date_column Is Nothing Then
MsgBox "Cant find date column", vbCritical
Exit Sub
End If
With date_column.EntireColumn
.NumberFormat = "mm/dd/yyyy;@"
End With
End With
End Sub