To suppress the pop up, and save the workbook IF IT'S
BEEN CHANGED (saves automatically the changes, if any),
you can write the following lines in the code area of the
workbook:
Private Sub Workbook_BeforeClose(Cancel as Boolean)
If Me.Saved = False Then Me.Save
End Sub
To do that:
1.Open the Visual Basic Editor (ALT+f11)
2.In the Project explorer, select ThisWorkbook; now in
the window of the right, where it says General,
select "Workbook" ; and in Proyect select "BeforeClose"
3.Write between the first and the last line:
If Me.Saved = False Then Me.Save
4. Close the Visual Basic Editor