Which method should you use to activate "Interactive Viewing"?

Preferences in Web Intelligence controls application-level settings such as locale and drill options, but document viewing mode is not configured there.

Preferences in InfoView (the BI launch pad) is the correct location to set the default viewing mode for Web Intelligence documents, including switching between Interactive, PDF, and other modes - this is a user-level portal preference that governs how documents open.

Document Properties controls metadata and data options for a specific document such as auto-refresh or query settings, not the viewing mode.

Report Properties controls individual report tab settings like page layout, not the interactive viewing activation.