This is code I received from another forum member, it's in ThisWorkbook object under BeforeSave:

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
Dim strSaveName As String
Dim var As Variant
Dim strNewPart As String

With ThisWorkbook
    If .Path = vbNullString Then
    strSaveName = "Underwriting (template).xlsm"
    var = Application.GetSaveAsFilename(strSaveName, fileFilter:="Excel Files (*.xlsm), *.xlsm")
    If var <> False Then
      Do While InStr(1, var, "template") > 0
        strNewPart = InputBox(prompt:="Enter the partial new name for saving")
        If Len(strNewPart) > 0 Then var = Replace(var, "template", strNewPart)
      Loop
    Else
      Exit Sub
    End If
    Application.EnableEvents = False
    .SaveAs var, FileFormat:=52
    Application.EnableEvents = True
    Cancel = True
  End If
End With
End Sub
It performs "okay" as long as you don't change your mind midway through saving.

I've tried various methods to change the file type during save, and none of them are without some sort of failure if you step outside the norm. My concern is that as a Macro-Enabled Template, the result file should default to Macro-Enabled Workbook out of the box too without having to resort to using VBA code to accomplish this. It may be that I'm missing a setting somewhere...