Stan,
You should not have to manually change the admin password for newly added/registered WAEs. Once the newly added WAE is listed as online, receives a full CMS update, and has no alarms present you should then have to login to the WAE CLI with the new admin password.
Note, I just tested this in my lab by de-registering a WAE from the CM, restoring it to factory defaults, changed the admin password from the default on the CM GUI, then registered the WAE to this CM. Once it was listed as online in the CM and all the alarms were cleared (I was missing the license at first), the next time I tried to telnet to it I had to use the updated admin password.
Hope this helps,
Mike Korenbaum
Cisco WAAS PDI Help Desk
http://www.cisco.com/go/pdihelpdesk