You seem to have found the box in Settings for the default Send PM.
You will also see when you send or reply a small box saying Save message to Sentbox. You need to check this before you send your message.
I had never seen that "Do you need to find someone?" button before, perhaps I hadn't scrolled down enough.
There did used to be a facility for searching for members by name on your Profile settings page. For some reason the Admins decided this was too radical and it was disabled.
The only ways you can check up on anyone these days is if they post in the forums or they send you a message. Or go through the list of members online - good luck with that one :afr2:
If you think you might want to contact someone again you can scroll through your messages if they are not deleted, add that person to your friends list or make a note of their userid, for instance yours is 640787. You can use the last to send a message to someone who has hidden his details. Method on request