You have the code in a Standard Module
This is a Workbook event and goes in the ThisWorkbook module and applies to all changes in all worksheets
Option Explicit
Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)
MsgBox "worksheet changed! " & Sh.Name
End Sub
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This is a worksheet event and goes in the module of the worksheet to which it applies. It only applies to that worksheet
Option Explicit
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
MsgBox "selected " & Target.Address
End Sub
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