1. Login to your Office 365 tenancy by navigating to https://portal.office.com.
2. Click on the Admin tile.
3. From the left navigation bar navigate to Admin Centers | Dynamics 365.
4. In the Dynamics 365 Administration Center navigate to the INSTANCES tab; then click the instance to update, followed by EDIT in the right dialog.

5. In the edit instance page under data encryption settings, click on the manage key button as shown here:

6. Click ok in the Are you sure you want to manage your encryption key dialog.
7. In the manage your database encryption key click on new as shown in this screenshot:

8. Enter your encryption key password in the download your new encryption key dialog; then click on OK, as shown here:

9. In the Are you sure you want to change your encryption key dialog click on yes.
10. Your new encryption key will automatically download. The key has a .pfx extension.