[QuestionAboutMyMac]

Hi, I am running El Cap and have an external drive with three partitions, one of which is password protected with FileVault.

Something happened in the last week or two—I must've clicked on a dialog box or something that asked me if I wanted to "always unlock" the volume, because now when I plug in the external drive, all three partitions pop up without my password being required for the FileVault'ed one.

Does anyone know how to change this back so that I am again prompted for the password for this FileVault'ed partition?

[P]

Sounds like you have stored the password for it in the Keychain - there is a checkbox for that when it asks for the password. You can edit stored passwords in the Keychain app, which is in Applications -> Utilities, IIRC. Find the stored password and delete it, and it should ask for the password every time again.

Note that the stored password is tied to the account, so if someone else connects the drive, the encrypted partition will stay locked.

[QuestionAboutMyMac]

Thank you, P!

Sure enough—that fixed my problem!
Thanks again!