In the Properties Inspector, selecting a Sara property displays a button letting you select a SaraSet to use for the current ScriptLine (or, if a SaraSet is already selected for the current ScriptLine, then it opens that SaraSet directly in the Saras Editor).
The Saras Editor allows you to edit Saras for the SaraSet you wish to use. Note that Q++Studio will ask you to confirm any modification made when you close the property editor. If you do not confirm, the SaraSet used to generate your diary will be the un-modified one.
See also: Saras applied to a Diary Output File.