Invoice numbering format cannot be retroactively applied to existing invoices - they retain their original numbers External file storage is one-way: once files are uploaded to external storage, they're deleted locally (backup before enabling if concerned) Client templates require Portal plugin - if Portal is deactivated, templates are not accessible (but data is preserved) Download links for external files expire after 30 minutes; long-term archival requires the original external storage system Company force-template policy is global; cannot be configured per-invoice