Bitlocker drives lock when rebooted

We have a Windows Server 2012R2 that is used as a Hyper-V host for two VMs. It has been working perfectly until recently. We changed the Admin login password out of necessity. Since then, when we reboot the server, the drives that are encrypted with Bitlocker require me to enter the authentication key (password) to unlock the drives. To do this, I go into the "File Explorer" and double click on the encrypted drive. It then brings up the "password" box. It is the same password as the admin login so I don't understand why it would require additional authentication.
Is there somewhere else I need to enter our new password?
Thanks so much for your assistance.