Can you install avast secure browser in a location other than C:\Program Files? I selected a different location when I installed avast free 19.1.4142.424 offline and it installed the antivirus in the location I wanted but the browser still ended up being installed in C:\Program Files\AVAST Software\Browser
Unless an option for a different installation path is provided in ASB (I haven’t seen one) during install you’d have to accept the default location.
If you know otherwise, provide a screenshot.