Options.RevisedPropertiesMark (Word)

Returns or sets the mark used to show formatting changes while change tracking is enabled. Possible return values are wdRevisedPropertiesMarkBold - In bold, wdRevisedPropertiesMarkColorOnly - In the designated color, wdRevisedPropertiesMarkDoubleStrikeThrough - Using double-strikethrough characters, wdRevisedPropertiesMarkDoubleUnderline - With double-underline characters, wdRevisedPropertiesMarkItalic - In italic, wdRevisedPropertiesMarkNone - Using a special character, wdRevisedPropertiesMarkStrikeThrough - Using strikethrough characters, wdRevisedPropertiesMarkUnderline - In underline.

Options.RevisedPropertiesMark = _ 
 wdRevisedPropertiesMarkDoubleUnderline