I think it's pretty smart you've come to thwack and ask.
Forcing a password-change on another account orphans its credentials, causing any monitors using the credential to fail with an appropriate error message. This is easy to fix if there's just a handful of credentials (you just reset the credential and put back the password).
When you change your own password, this is not the case. I am not 100% sure about using the account configuration pages to change your your password, but I do know that "My Settings" is the safe way to do this.
- Login as the admin.
- Go to "My Settings".
- Change your password.
I will try and post the results.