When changing a password on an already existing account (e.g. Amazon) , do I first have to manually change it through Amazon and then enter the change through my Avast password manager? Or can I somehow do it through Avast?
If you're changing the password on a site, (Amazon or any other) That change needs to be made on that site first.
The next time you visit that site, if Avast auto enters the password, you'll get an error message since the password was change.
Enter the new password manually and Avast will ask if you want to update the password for that site. Select yes and from then on,
Avast will auto fill the new password for you when you visit that site.