Command /qwa without arguments shows the usage
/qwa hide - hides currently watched quests
/qwa restore - restores watched quests hidden by /qwa hide
Restore doesn't remember hidden quests across sessions
/qwa hide complete - hides quests that are complete and waiting to be returned
/qwa watch profession - adds all current profession quests to watchlist
/qwa autowatchzone - toggles between autowatchzone on or off
Autowatchzone is on by default and also the state is not remembered across sessions. If you want to permanently set the default to off, open the file QuestWatchAssistant.lua in a text editor and on the first line, change the true to false.
QWA does not hide the World Event or Zone quests or other "special" quest types not changeable from quest list window.
More ideas for features are welcome.
It's also possible to make macros for more complicated sets of functionality, for example
/qwa hide
/qwa watch profession
/qwa hide complete
To only show the uncompleted profession quests, often workorders.