Minor point - I can’t find how to edit my signature. I know it’s possible in the Profile but I don’t see the link for changing it. I see my signature is on my posts and in my Profile, but how to edit it. Could it be something to do with not having visited and posted on the forum for a few months until a day or two ago?
Thanks
You haven’t made enough post to earn that ability. 
I believe the magic # is 20.
But once you do reach that magic number of 20 posts and want to know how to edit or make your Signature:
Go to PROFILE on the top of the main forum page > Modify Profile > Forum Profile Information > Signature. Enter information about your system like the Operating System (OS), RAM, browser, security software, what version and product of Avast you use, your firewall, and other items you wish to mention. See my signature or others as an example. The purpose of this is so that we can offer pertinent advice. Thank you.