Only the system security officer can change the system encryption password.
Changing system encryption passwords
In the server, click Databases to display a list of available databases.
In the database list, right-click the database you want.
Select System Encryption Key.
Select Alter System Encryption Password.
Enter the current password in the Old Password field.
Enter a new password of six or more characters.
Reenter the new password in the Confirm New Password field.
Click OK.