I have reinstall the program a couple different times with the same unwanted update occurring. EACH TIME has been a CLEAN install after running the removal tools.
You're making the assumption that the update process, which was apparently forced, is trouble free, then assigning the blame for the subsequent failure on the latest version.
It doesn't sound as if you've attempted to install
the latest version cleanly. I believe that would lead you to a successful configuration.
But hey, if you're fed up with Avast, I can't blame you. Maybe it's time to move to something else, even though folks are telling you the latest version CAN work.
-Noel