A family of Microsoft word processing software products for creating web, email, and print documents.
You might do better with the following. It will take an age to run, but it will randomly format each character in a document.
Sub JumbleLetters()
Dim oDoc As Document
Dim oText As Range
Dim nList As Long, nSize As Long, iChar As Long
Dim FontList As Variant, FontSize As Variant
Set oDoc = ActiveDocument
Set oText = oDoc.Range
FontList = Array("Arial", "Times New Roman", "DejaVu Sans", "Century Gothic")
FontSize = Array(12, 13, 13.5, 14, 16.2, 17)
nList = UBound(FontList)
nSize = UBound(FontSize)
For iChar = 1 To oText.Characters.Count
oText.Characters(iChar).Font.Size = FontSize(Int(Rnd() * nSize))
oText.Characters(iChar).Font.name = FontList(Int(Rnd() * nList))
DoEvents
Next iChar
End Sub