Bold/Red a specific word in a cell

Private Sub Worksheet_Change(ByVal Target As Range)

    Dim myword As String
    Dim i As Integer
    Dim n As Integer
   
    myword = "update"
    
    If Not Intersect(Target, Range("D:D")) Is Nothing Then
    
        If InStr(Target, myword) > 0 Then
        
            myarray = Split(Target, myword)
            mycount = UBound(myarray)
            
            'Start search at position 1. (Allows for multiple occurrences)
            i = 1
            For n = 1 To mycount
                i = InStr(i, Target, myword)
                    Target.Characters(i, 6).Font.Color = vbRed
                    Target.Characters(i, 6).Font.Bold = True
                'start next search after previous
                i = i + Len(myword)
            Next
        End If
        
    End If


End Sub