1. when there is a detection, what actions do you have avast take ?
If you allow antonymous action, you have no control over what action to take. I would suggest you change your scan settings, see attached image and check that box to see other actions you want to take. For me that would be No Action, on completion of the scan you should be able to determine what actual action you want to take.
2. Personally I feel that on-demand scans are much depreciated.
- With a resident (on-access) scanner the need for on-demand scans is much depreciated. For the most part dormant/inert files are being scanned, the other active files are going to be scanned by the resident shields when they are activated.