Time Machine - Encrypted Backups - How to Have TM Prompt User For Password Again I'm using Time Machine with encrypted backups on my macbook air.  A few weeks ago, I selected "remember my computer," when typing in the password to allow my time machine to backup, so now, when I plug in my external drive, it doesn't ask me for the password.  I've been looking for the option to switch it back recently and can't find it anywhere.  Anyone know where this would be located?
I am not sure, but this may work. Try this:


Open Time Machine from System Preferences 
Turn Time Machine Off
Select Backup Disk and turn Time Machine back on
Choose to Encrypt Back Up
Re-enter your password, or create a new password
Wait for it to encrypt
Turn Time Machine off, and then on again to test it out