You should not be modifying a document that way. rather, you should create a Style with the desired characteristics (or modify an existing one) and apply that. For example, the following macro does what you ask by modifying & applying Word's 'Normal' Style:
Code:
Sub FormatActiveDocument()
Application.ScreenUpdating = False
With ActiveDocument
With .Styles(wdStyleNormal).Font
.Name = "Arial"
.Size = 14
.ColorIndex = wdDarkBlue
End With
With .Range
.Style = wdStyleNormal
.ParagraphFormat.Reset
.Font.Reset
End With
End With
Application.ScreenUpdating = True
End Sub