An annoying behaviour of the simpleconnect component is the fact that it will remember your username (and even log you in automatically) between sessions. Some people might not be bothered by this but I never liked it much and decided to hack it a bit, here's how.

The username is stored inside a SharedObject (SO) and that's the bit that needs disabling. Start by selecting the SimpleConnect component in the library and select edit.
The 'else' statement on line 94 of the ActionScript on the Actions layer needs disabling. Commented out the following lines:

else {
   this.local_so = SharedObject.getLocal("FCUsername", "/");
   if (this.local_so.data.username != null) {
   this.username = this.local_so.data.username;
   this.changeName_btn.setEnabled(true);
  }
}

And again there is a reference to the same SO further down, it's best to comment this out as well (line 139):

//this.local_so.data.username = this.username;

And that's it. Happy communicating.