I set the on-access scanner to High when I first installed Avast. Is customising settings even better at detection?

Well better… it depends what that word means for you. Customizing the settings will let you set a lot of other options, an yes, to make the scanning even more intensive (you can ultimately set the on-access scanner to test every file on both open and close) but that doesn’t really mean that you should do that as there is probably no chance that this will pick virii that wouldn’t be picked anyhow, and it would certainly have negative impact on overall system performance…

So as always, it’s a matter of finding a balance between performance and functionality, and we believe our preset values for the Normal and High levels do pretty good job at this…