This works for me and is invaluable. Create a macro thus; mine is named Ar10chg because I use it to change everything to Arial 10. All the font sizes, underscores, bold, italic, and font colors are unchanged, but everything becomes Arial 10. Be sure to create a backup first!

Sub Ar10chg()
'
' Ar10chg Macro
' Macro recorded 11/7/2015 by Administrator

Selection.WholeStory
With Selection.Font
.Name = "Arial"
.Size = 10
End With
End Sub