system
1
Many thanks to bob3160 for the information that Avast 2017 On-line Security saves user settings as cookies in FireFox.
This must be a Very Bad Idea, particularly for those who ask FF to clean the cookie cache On Shutdown - if only to control the build-up of cookies. FF disposes of everything and there is no way to set exceptions. End result is that I lose the global settings for Avast On-line Security each time I close FF.
Using about:config in FF there is the setting privacy.clearOnShutdown.cookies. This is a Boolean setting and there is no option of defining exceptions.
Not easy to understand why Avast has chosen to use cookies in this way, particularly as a security product should enable the user to remain secure.
Is there a work around in this instance?
In the next software update should Avast store the setting data under AppData in Windows rather than as a cookie?
bob3160
2
Reported to Avast. Let’s see if they have an answer. 
Rather than use the FF > Delete History option try using CCleaner instead.
CCleaner > Options > Cookies.
This allows you to save cookies that you don’t want to be deleted so that when you use CCleaner to clean your FF history (it actually does a more comprehensive job than FF anyway) it will exclude those saved cookies.
bob3160
4
That would work as a temporary stop gap but, it isn’t a permanent fix.
