Your question is unrelated to the topic or the text you quoted, so it may be better to put this in a topic of its own with a Title more appropriate, like Schedule Boot-Time scan option missing after Update.’

If this doesn’t quickly resolve it, that is what I suggest you do.

If you haven’t rebooted after the update, do so.
If no change, try a repair of avast. Add Remove programs, select ‘avast! Anti-Virus,’ click the Change/Remove button and scroll down to Repair, click next and follow. You need to be on-line to do this.