Flag column if changed

How or where would the flagging be recorded?

Internally within Visual Basic for Applications code for later interrogation, visually in-cell somewhere within the same column, or elsewhere (such as a different worksheet, or in an external file, for example)?

I am just going to put a 1 in row 16 of that column  I have an if statement that will trigger logic if the column has changed, but I don't know how to flag if the column has changed.

There could be anywhere from 50 to 4,000 rows of data  - I just need to now if just one piece has changed in the one column .. that is it.

Mine works on column C but that's easily changed.

Something like this may be what you are looking for...

Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)

  Dim objCell                                           As Range
  
  On Error Resume Next
  
  Application.ScreenUpdating = False
  Application.EnableEvents = False
  
  For Each objCell In Target
  
      DoEvents
      
      If objCell.Row <> 16& Then
         Me.Cells(16&, objCell.Column).Value = 1
      End If ' If objCell.Row <> 16& Then
      
  Next objCell ' For Each objCell In Target
  
  Application.EnableEvents = True
  Application.ScreenUpdating = True

End Sub

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Please see the attached workbook.

PS. It could be improved by only processing one cell from each column in the Target range, but typically the Worksheet_Change(...) event will only ever process one cell at a time anyway, so that approach may well be just for very extreme cases.

The code above copes with changing multiple cells at once, though.
Q-28702863.xlsm

Simply this where 3 represents column C..

Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Target, Columns(3)) Is Nothing Then
    Cells(16, 3) = 1
    End If
End Sub

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I'm glad I was able to help. If you actually chose one of my solutions that used 'ActiveCell', you should substitute 'Target'.

In my profile you'll find links to some articles I've written that may interest you.
Marty - MVP 2009 to 2015, Experts-Exchange Top Expert Visual Basic Classic 2012 to 2014

You're welcome, BirdWatchers.

(Sigh)