Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
Dim Bereich As Range
'nur in Spalte A
Set Bereich = Intersect(Range("A:A"), Target)
If Not Bereich Is Nothing Then
For Each Bereich In Bereich
With Bereich
.Font.Bold = False
.Font.ColorIndex = xlAutomatic
If Len(.Value) > 63 Then
'Zeichen an 64. Stelle
With .Characters(Start:=64, Length:=1).Font
.ColorIndex = 3
.Bold = True
End With
End If
End With
Next Bereich
End If
End Sub