Limit the prefix vba function to dynamic range - vba

Question

enter link description hereI want to limit below vba code to the column A in dynamic range ONLY. Right now if I enter something outside the range, it shows error and disrupts other functions in Workbook_SheetChange.
I attach my file for easy ref.
Please HELP ! HELP
'Formate Column A
If Target.Column = 1 Then
Dim s As String
Dim arr As Variant
s = Target.Value
If s = "" Then
Target.NumberFormat = "General"
Else
With CreateObject("vbscript.regexp")
.Pattern = "[^0-9]"
.Global = True
.IgnoreCase = True
arr = Split(Application.Trim(.Replace(s, " ")), " ")
End With
Target.Value = arr
Target.Value = Target.Value * 1
Target.NumberFormat = """REQ0000000""General"
End If

Answer 1

'Excel file link : https://drive.google.com/file/d/13w-AbgY83g02qHGqBrHr_6N26UkNpWKr/view?usp=sharing
Private Sub Workbook_BeforeClose(Cancel As Boolean)
Call Module1.DeleteCheck
End Sub
Private Sub Workbook_Open()
Call Module1.CreateCheck
'Application.MoveAfterReturnDirection = xlToRight
'Application.MoveAfterReturn = True
End Sub
Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)
Select Case Sh.Name
Case "Agents"
Exit Sub
Case Else
End Select
If Target.Column > 4 Or Target.CountLarge > 1 Then Exit Sub
If Target.Row = 1 Then Exit Sub
Application.EnableEvents = False
If InStr(1, Cells(Target.Row, "A"), "REQ") <> "" And Cells(Target.Row, "B") <> "" Then
Cells(Target.Row, "C") = ActiveSheet.Name
Cells(Target.Row, "C").Font.Name = "Times New Roman"
Cells(Target.Row, "C").Font.Size = 12
Cells(Target.Row, "C").HorizontalAlignment = xlRight
Cells(Target.Row, "D").ShrinkToFit = True
Cells(Target.Row, "A").Font.Name = "Times New Roman"
Cells(Target.Row, "A").Font.Size = 12
Cells(Target.Row, "A").HorizontalAlignment = xlLeft
Cells(Target.Row, "B").Font.Name = "Times New Roman"
Cells(Target.Row, "B").Font.Size = 12
Cells(Target.Row, "B").HorizontalAlignment = xlLeft
End If
'Formate Column A
If Target.Column = 1 Then
Dim s As String
Dim arr As Variant
s = Target.Value
If s = "" Then
Target.NumberFormat = "General"
Else
With CreateObject("vbscript.regexp")
.Pattern = "[^0-9]"
.Global = True
.IgnoreCase = True
arr = Split(Application.Trim(.Replace(s, " ")), " ")
End With
Target.Value = arr
Target.Value = Target.Value * 1
Target.NumberFormat = """REQ0000000""General"
End If
End If
'Set Cell Movement within The Range
'https://www.mrexcel.com/board/threads/set-movement-of-cells-in-dynamic-range-only.1172539/
If Target.CountLarge > 1 Then Exit Sub
Dim rng As Range
Set rng = Range("A1").CurrentRegion
If rng.Rows.Count > 1 Then
Set rng = Intersect(Target, rng.Offset(1, 0).Resize(rng.Rows.Count - 1, rng.Columns.Count))
Else
Set rng = Nothing
End If
If Not rng Is Nothing Then
If Target.Column = 2 And Not (IsEmpty(Target)) Then
Target.Offset(, 2).Select
Else
Target.Offset(, 1).Select`enter code here`
End If
End If
Application.EnableEvents = True
End Sub
Private Sub Workbook_SheetBeforeRightClick(ByVal Sh As Object, ByVal Target As Range, Cancel As Boolean)
Select Case Sh.Name
Case "Agents"
Exit Sub
Case Else
End Select
If Target.Column <> 5 Or Application.CountA(Cells(Target.Row, 1).Resize(, 2)) < 2 Then Exit Sub
Cancel = True
Call Module3.SelectOLE3
End Sub
Private Sub Workbook_SheetSelectionChange(ByVal Sh As Object, ByVal Target As Range)
Select Case Sh.Name
Case "Agents"
Exit Sub
Case Else
End Select
If g_blnWbkShtSelChange Then Exit Sub
If Selection.Count = 1 Then
If Not Intersect(Target, Range("C1")) Is Nothing Then
g_blnWbkShtSelChange = True
Call Module1.CheckSheet
End If
End If
End Sub