To change annotation and asset visibility after creating an activity, choose Settings.
Open Peer Review Setting
To do open peer review configure your activity to:
Open Asset Visibility + Public Annotation Visibility
When changing Annotation Visibility in Settings, the new setting can be applied to all assets currently in the activity.
If you want the new setting to override custom-visibility settings made at the document level, choose the second box, "Include assets with custom selection."
For example, if some assets were manually turned to Private, they will stay Private unless "Include assets with custom selection" is selected.