The default setting for the Watched Threads appears to be 'anything I ever posted in'. 
This means lots of Alerts, which is not quite how I want my Alerts to work.
It appears that I need to go to each thread in turn and 'Unwatch' it - but I'm sure there is a collective 'Unwatch All' box to tick.
Where will I find it, please ?

This means lots of Alerts, which is not quite how I want my Alerts to work.
It appears that I need to go to each thread in turn and 'Unwatch' it - but I'm sure there is a collective 'Unwatch All' box to tick.
Where will I find it, please ?