If I switch from Premium to Free, will I lose my Premium data and settings?

No, but as a Free member you will no longer be able to access them, with the exception that your portfolios will still be accessible in the dashboard. However, should you decide to re-enroll in a Premium plan, all of your Premium items (such as watchlists, screeners, notes, tags etc.) will be restored.

How do I update my credit... How do I cancel my Premium...