To change the sound, find a .wav file you like better. Make a copy of it, rename the copy to
Alarm.wav
and then move that file into
C:\Program Files\Maximizer\MaData6
replacing the "Alarm.wav" that is already there.
To change the volume, use a sound editor to edit the .wav file. An excellent shareware sound editor is GoldWave:
http://www.goldwave.com/.