You can configure the integration on several levels. At the global level, all Projects, backlogs and QA sections in the database are affected. You can override and change specific settings for the various Projects, backlogs and QA sections. The recommended way is to configure the Perforce server settings globally, while leaving the "Enable perforce integration" check box unchecked and then enabling the integration on only the projects and views that you want to be accessible from Perforce.
Accessing the global Perforce Integration settings:
Accessing the Project Integration settings (configures main project, the backlog and the QA sections):
Accessing the QA Perforce integration settings:
Accessing the backlog Perforce integration settings: