If you weren’t able to write the key down before it disappeared from view, you have to disable FileVault encryption and re-enable it to generate a new recovery key: ...

A bug in OS X 10.7.3 exposes legacy FileVault users, but there are some workarounds to prevent this from happening.

All good things must come to an end, we’re told, and macOS 10.13 was the very end of the original FileVault, Apple’s file encryption format introduced in OS X Panther 10.3. With the original ...

To turn off automatic login on your FileVault 2-encrypted Mac, go to System Preferences > Users & Groups > Login Options and make sure that "Off" is selected from the drop-down.