I formatted my hard disk as APFS encrypted, then installed Mojave. When I did this with High Sierra I was asked for BOTH the disk password and then my login. Under Mojave my User login now 'automatically' unlocks the disk (no separate disk password is requested). For added security I WANT to be asked for both the Disk password and the user login. I assume the disk password is 'stored somewhere in my keychain. How do I remove the 'stored' disk unlock password from my account so that I have to use both passwords to unlock my computer?