I want Back to My Mac to require an administrator password every time I connect. How do I do so?
The portable computer is 10.7. The desktop is 10.8
I don't know if this will work, but you might give it a try:
Go into Keychain Access and find the entry for your mac on Back To My Mac (see here: http://support.apple.com/kb/HT4907) and delete it.
When you log in again, if it offers to remember the password, don't check the box.