If this is a Linked Word Document, Try going to File>Project Settings >Next and Click on Edit for Word Document conversion Settings, and
Select Edit and it would prompt you with all avauilable tags along with their Appearance, Example in Word and Robohelp.
Check your tag in the List and Select "Source " in Drop Down of RoboHelp Style.
And try to Select that and observe if the Appearnace or Style is imporved.
Alternately, if you want you can import the Word Doccument and its assocaiated CSS file would be imported too and you can make changes directly to CSS and reapply them.
thank you, Anjaneai.