This section of the forum is intended for reporting possible bugs in the software...
In layout mode, double click the button to bring up button setup... You can use this dialog to discover the name of the script being performed when the button is edited. Now bring up Manage Scripts, find this same script and open it. Scan down until you find a Show Custom Dialog script step in the script and double click it. You'll now see the dialog where these buttons were named.
Changing the names here only changes the names that appear in the custom dialog. It will not change what happens when the button is clicked. You'll then need to examine the script and look for If [Get ( lastmessageChoice ) = ... steps for each of these button. That section of the script will also need to be updated if you need different things to take place now that the people listed on the buttons have changed.
Note: There are alternatives to this approach that would eliminate the need to modify the system design everytime your personnel change.