Found a bug
It is possible to change within the update settings of Avast to turn off Streaming updates, even if all parts of the program is shielded with a password.
Steps to reproduce (Win7): Right click on the Avast icon --> update --> choose program or definitions. Program asks for the password --> press cancel. Now you can change the settings of the update process, however, only ticking/unticking of streaming updates will result in changing the setting.
Changing the settings of updating the program/definitions to manual will not stick. Also if Streaming updates are turned off, Avast will continue to report that all is ok...