Was the OP talking about Avast updates or the new, unwanted, application updater?
I updated from Avast 7 to 8 earlier this week and the only custom install option was the usual attempt to get you to use Google Chrome. No mention of the application updater that I saw.
What I can't find is an option to just turn it off, the updater entriers in the Settings appear only to apply to Avast updates, not application updates.
I've just gone through the list of applications it has just tried to persuade me to update (most were already updated) and told it to Ignore them in future.
This seems like a very crude and ill-though out addition to Avast. I don't want or need Avast scanning my system and producing pop-ups every time I start my computer telling me one or more of my programs is in "critical" need of an update. The scan slows down my system whilst it is doing this and I am well aware of what needs updating anyway. The programs themselves annoy you with reminders unless you have switched those reminders off too.
A main menu button to turn this function on and off as required by the user might actually be useful but without this option, as it appears to be, is just an annoyance we don't need.