Start with the phone itself
A document app cannot compensate for an unprotected device.
Use the security controls available on your iPhone and treat the device passcode as protection for everything behind it, not just the lock screen.
Then look at the documents themselves.
Do not confuse “available” with “everywhere”
The common shortcut is easy: photograph an ID, save a PDF, send it to yourself, download it again, then screenshot the bit you need.
Now the same sensitive document exists in Photos, Files, Messages, Mail and Downloads.
Convenient once. Difficult to reason about later.
A better system keeps the number of active copies small enough that you know where they are.
Keep only the documents that earn a place on the phone
Start with documents you actually need when you are away from the physical folder: identification details, insurance information, vehicle papers, travel documents, memberships or similar references.
Do not upload an entire lifetime archive just because storage is available.
The smaller active set is easier to review when something expires, changes or no longer needs to travel with you.
Separate the quick answer from the full document
Most of the time you need one field, not six pages.
A policy number. An expiry date. A document number. A membership ID.
Keep that quick-reference layer easy to reach, but keep it connected to the source. When the detail is not enough, you should still know exactly which document it came from.
Share narrowly
If someone needs one document, share one document.
Avoid solving a narrow request by exposing a broad folder full of unrelated personal information.
Panza follows that model: owners share individual documents with viewer or editor roles that can later be changed or revoked.
Clean up after the moment passes
The dangerous clutter is often not the organized copy. It is the temporary copy that stopped feeling temporary.
After a trip, application, repair or insurance claim, check Photos, downloads and message threads for sensitive duplicates you no longer need.
A secure document habit is partly about storage. It is also about deletion.