Ho Southwest
The alerts are stored in the Registry - if you are happy editing the Registry, you can change the order of entries there - HKEY_LOCAL_MACHINE\SOFTWARE\AirNav Systems\ANRB\1\General - look for memo1text and following entries.
If you aren't comfortable doing that, then I suggest emptying the Alerts entries, (possibly copying them into Notepad for sorting and later pasting back) closing RadarBox, restarting, and re-entering the alerts in the order you want.
I don't know if I'm trying to teach Granny to suck eggs, but if you aren't experienced with registry editing, use the second option - playing with the registry can be very bad for your mental health!
Hope that helps!
Rod