Hello Try this code based on Mr. Leith Ross's code
'Reference : Microsoft Visual Basice for Applications Extensibility 5.3
'----------------------------------------------------------------------
Sub ChangeMacro()
Dim Wb As Workbook
Dim Ws As Worksheet
Dim VBComp As Object
Dim VBProj As Object
Dim Code As String
Dim WksName As String
Set Wb = ActiveWorkbook
For Each Ws In Wb.Worksheets
WksName = Ws.CodeName
Set VBProj = Application.VBE.ActiveVBProject
Set VBComp = VBProj.VBComponents(WksName)
With VBComp.CodeModule
Code = .Lines(1, .CountOfLines)
Code = Replace(Code, "Replace This", "Nice Work!")
.DeleteLines 1, .CountOfLines
.InsertLines 1, Code
End With
'There Is No Way To Hide All The Sheets In The Workbook
'ws.Visible = xlSheetHidden
Next Ws
MsgBox "Done...", 64
End Sub