The following macro should do that, BUT make sure that you have a copy of
the documents so that there a no surprises if the result is not exactly what
you want

Dim MyPath As String
Dim MyName As String
Dim MyDoc As Document
Dim MyTable As Table

'let user select a path
With Dialogs(wdDialogCopyFile)
   If .Display() <> -1 Then Exit Sub
   MyPath = .Directory
End With

'strip quotation marks from path

If Len(MyPath) = 0 Then Exit Sub

If Asc(MyPath) = 34 Then
   MyPath = Mid$(MyPath, 2, Len(MyPath) - 2)
End If

'get files from the selected path
'and set the AllowAutoFit property for each
MyName = Dir$(MyPath & "*.*")
Do While MyName <> ""
   Set MyDoc = Documents.Open(MyPath & MyName)
   For Each MyTable In MyDoc.Tables
       MyTable.AllowAutoFit = True
   Next MyTable
   MyDoc.Close wdSaveChange
   MyName = Dir
Loop