"Store Value in DICT and Change Color if not exist"

i have data in col A example in A1 = "a1234" then store to dict
after store ,in events Sub Worksheet_Change(ByVal Target As Range)
while i am edit value in A1 become "a1234 New Value" then New Value become Font.Bold how
can do ,please help me

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column = 1 Then
 Call test
End If
End Sub
 
Sub test()
Dim v As Range
With CreateObject("Scripting.dictionary")
 For Each v In Columns("A:A").SpecialCells(2)
  If Not .exists(r) Then
      .Add v.Value, v
   End If
 Next v
  For Each r In .keys
   For Each r1 In Columns("A:A").SpecialCells(2)
   If r = r1 Then
      Right(r1, 4).font.Bold = false  
   Else
    Right(r1, 4).font.Bold = True
   End If
   Next
  Next
End With
End Sub