Run a Worksheet_Change function when the value of cell $O$2 changes

Question

I need to run a macro when the value in cell $O$2 changes.

I have a workbook with 100+ sheets each tracking an individual work ticket. Each sheet is exactly the same (except for work notes). I want to run a macro named, "Insert_NEW" when I hit ENTER and the cell value of $O$2 changes versus manually clicking a button to run the macro 100+ times a day. I know I'm overlooking something simple, but I've spent almost 4 hours trying to add this feature when it can probably be resolved in 1-2 minutes. The goal is to embed the updated script between the EnableEvent update true/false. Thank you in advance for any assistance.

I have this existing script:

Private Sub Worksheet_Change(ByVal Target As Range)
    If Target.Column = 15 Then
        Application.EnableEvents = False
        Cells(Target.Row, 27).Value = Date + Time
        Application.EnableEvents = True
    End If
End Sub

I'm trying to add the script below to run the existing functional macro named "Insert_NEW".

    If Target.Address = "$O$2" Then
        Call Insert_NEW
    End If

I've also tried

    If Not Intersect(target, Range("$O$2") Is Nothing Then
        Call Insert_NEW
    End If

@TimWilliams - This is what I added as a module after removing the private subs from the rest of the workbook:

Private Sub Worksheet_Change(ByVal Target As Range)
    If Target.Column = 15 Then
        Application.EnableEvents = False
        Cells(Target.Row, 27).Value = Date + Time
        Application.EnableEvents = True
    End If
    If Not Intersect(Target, Range("$O$2")) Is Nothing Then
        Call Insert_NEW
    End If
End Sub

Answer 1

This works for me, in the worksheet code module for a single sheet:

Private Sub Worksheet_Change(ByVal Target As Range)
    Dim c As Range
    
    Set c = Application.Intersect(Target, Me.Range("O2"))
    
    If Not c Is Nothing Then 'was O2 updated?
        MsgBox "O2 changed"
        Insert_NEW Me  'pass worksheet to your sub
    End If
End Sub

If you want to track changes to O2 on any sheet in the workbook, remove any existing Worksheet_Change code from individual worksheet modules, and add this code in the ThisWorkbook code module:

Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)
    Dim c As Range
    
    Set c = Application.Intersect(Target, Sh.Range("O2"))
    
    If Not c Is Nothing Then 'was O2 updated?
        MsgBox "O2 changed on sheet '" & Sh.Name & "'"
        Insert_NEW Sh   'pass worksheet to your sub
    End If
End Sub

Your called sub goes in a regular code module:

Sub Insert_NEW(ws as Worksheet)
    With ws
         '...do stuf with `ws`
    End With
End Sub

Make sure events are turned on: in a regular module run this -

Sub EventsOn
    Application.EnableEvents = True
End sub