Sorzy,
Whilst it’s possibly not on topic for this thread, I find the wording of that box hard to understand. I personally didn’t install Chrome, so having a box which is NOT ticked by default saying “Do not use Chrome as the Avast default Browser” doesn’t make a lot of sense, however with the thought that Avast might try to use what isn’t there, I’ve ticked it just in case. Would help if there was some up to date instructions available.