Your library is encrypted on this device with your passphrase before it goes to Cloudflare. Use the same passphrase on every device. If you forget it, the synced copy can't be recovered.

Sync is off.

Spreadsheets: upload an .xlsx or .csv with columns headed Title, Year, Quality and Size (or just those four in columns A to D). New films are added; films already in the library are skipped, but any blank year, quality or size is filled in.