Look for last column that has a specific value - excel

Question

I have a file with 8+ "Sales" columns spreading throughout my worksheet. I tried the following code to do: If any Sales cells have "Title Transfer" then the 51st column would have an "x".
Option Explicit
Public Const colTTransfer As Long = 51
Private Sub Worksheet_Change(ByVal Target As Range)
Dim lastColumn As Long
Dim counter As Long
lastColumn = Me.Cells(1, Me.Columns.Count).End(xlToLeft).Column
If Me.Cells(1, Target.Column).Value = "Sales" Then
For counter = 1 To lastColumn
If Me.Cells(Target.Row, counter).Value = "Title Transfer" Then
Me.Cells(Target.Row, colTTransfer).Value = "x"
End If
Next counter
End If
End Sub
However, I realised there was more to my original purpose and the above codes weren't flexible. My codes check any Sales cells that are Title Transfer but they didn't reflect the changes of other Sales cells within the same rows.
For example, if a cell in my 1st Sales column has Title Transfer then the 51st column would return an x. And if the cell in the 2nd Sales column within the same row has a different value, e.g. Green, the x in the 51st column should be removed (which my codes can't)
So I'm wondering if there is a way to only return x for the last Sales column that has Title Transfer?
For example, assuming these events happen in the same row where:
1st Sales column has Green and 51st column remain blank
2nd Sales column has Title Transfer and 51st column has x
3rd Sales column has Rollup and 51st column turns blank
4th Sales column has Red and 51st column remains the same
5th Sales column has Title Transfer and 51st column now has x
and so on
This what my data looks like:
| Title | Engine Family | Market Segment | Customer | Engine Model | S/N | Build Spec | ACTL.FINISH | Sales Order | Item | Committed Date | EPS Date | Target | Sales | Production | Day 1 | Status | Sales | Production | Day 2 | Status | Sales | Production | Day 3 | Status | Sales | Production | Day 4 | Status | Sales | Production | Day 5 | Status | Sales | Production | Day 6 | Status | Sales | Production | Day 7 | Status | Sales | Production | Day 8 | Status | Status | Comments | MB51 Shipped | FPS? | Plant | Title Transfer |
|--------|------------------|----------------|----------|--------------|-----|------------|-------------|-------------|-------|----------------|------------|--------|-------|------------|-------|--------|----------------|------------|-------|--------|--------|------------|-------|--------|-------|------------|-------|--------|----------------|------------|-------|--------|--------|------------|-------|--------|----------------|------------|-------|--------|-------|------------|-------|--------|--------|----------|--------------|------|-------|----------------|
| Rollup | PS | APU | HAC | T-62T-46C12 | 1 | BS1 | 0000-00-00 | 0 | 0 | 2019/12/31 | 2019/12/31 | | Green | | | | Title Transfer | | | | Rollup | | | | Red | | | | Title Transfer | | | | Rollup | | | | Title Transfer | | | | | | | | | | | | | x |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Link to sample
Please advise how I can make it work that way. Any help is highly appreciated. Thank you

Answer 1

You just need to move the Title Transfer field update to the end of the loop and evaluate each Sales column to the end. The updated code should resolve that.
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column < colTTransfer Then
If Trim(UCase(Me.Cells(1, Target.Column).Value)) = "SALES" Then
Dim lastColumn As Long
Dim counter As Long
Dim rowIsTitleTransfer As Boolean
lastColumn = Me.Cells(1, Me.Columns.Count).End(xlToLeft).Column
rowIsTitleTransfer = False
' loop
For counter = 1 To lastColumn
If Trim(UCase(Me.Cells(1, Target.Column).Value)) = "SALES" Then
rowIsTitleTransfer = Me.Cells(Target.Row, counter).Value = "Title Transfer"
End If
Next counter
' assign title transfer column
If rowIsTitleTransfer Then
Me.Cells(Target.Row, colTTransfer).Value = "x"
Else
Me.Cells(Target.Row, colTTransfer).Value = ""
End If
End If
End If
End Sub

Answer 2

I found my answer. Still, thank you for everyone's help
Private Sub Worksheet_Change(ByVal Target As Range)
Dim r As Range, r1 As Range, lastColumn As Long, counter As Long
Dim MaxCol As Variant, rg As Range, j As Long
If Not Intersect(Target, Range("N:AP")) Is Nothing And Target.Column Mod 4 = 2 Then
Set r = Intersect(Target, Cells(1, 1).CurrentRegion, Columns(Target.Column).Resize(, 3))
Call DoCells(r)
End If
' Get last column based on first row
lastColumn = Me.Cells(1, Me.Columns.Count).End(xlToLeft).Column
If Me.Cells(1, Target.Column).Value = "MB51 Shipped" Then
For counter = 1 To lastColumn
If (Me.Cells(1, counter).Value = "Sales" Or Me.Cells(1, counter).Value = "Production") And IsEmpty(Me.Cells(Target.Row, counter).Value) Then
Me.Cells(Target.Row, counter).Value = "Rollup"
End If
Next counter
End If
If Not Intersect(Target, Range("N:AP")) Is Nothing And Target.Column Mod 4 = 2 Then
If Target.CountLarge > 1 Then Exit Sub
Set rg = Range("N" & Target.Row & ":AP" & Target.Row)
MaxCol = 0
For j = Columns("AP").Column To Columns("N").Column Step -4
If Cells(Target.Row, j) <> "" Then
If j > MaxCol Then MaxCol = j
End If
Next
If MaxCol Mod 4 = 2 Then
If Cells(Target.Row, MaxCol).Value = "Title Transfer" Then
Cells(Target.Row, 51).Value = "x"
Else
Cells(Target.Row, 51).Value = ""
End If
End If
End If
End Sub