Is your C:\Program Files\HTC\Aces High II\settings\sounds.cfg "read-only" ?
Here is mine ... did you try to manually update this file and see if it works. If you manually change the file and the sound volumes don't stay, then I would say it's a bug.
0.570000,Master
0.520000,eng
0.800000,engstart
0.800000,engoff
0.800000,damage1
0.800000,stall
0.800000,hit
0.800000,hit_1
0.800000,hit_2
0.800000,hit_3
0.800000,hit_4
0.800000,hit_5
0.800000,hit_6
0.800000,hit_7
0.800000,m2
0.800000,m2
0.800000,weapon
0.800000,tire
0.800000,gear
0.800000,flaps
0.800000,stress
0.800000,wind
0.800000,veng
0.800000,vstart
0.800000,vstop
0.800000,tread
0.800000,explode2
0.800000,explode1
0.800000,explode3
0.800000,explode4
0.800000,beng
0.800000,bstart
0.800000,bstop
0.800000,wake
0.800000,check6
0.800000,jeng
0.800000,jstart
0.800000,jstop
0.800000,rato
0.800000,eng
0.800000,engstart
0.800000,engoff
0.800000,
0.800000,veng
0.800000,vstart
0.800000,vstop
0.800000,wheel
0.800000,beng
0.800000,btart
0.800000,bstop
0.800000,
0.800000,jeng
0.800000,jstart
0.800000,jstop
0.800000,
0.800000,veng
0.800000,vstart
0.800000,vstop
0.800000,tread
0.800000,gstrike1
0.800000,gstrike2
0.800000,gstrike3
0.800000,gstrike4
0.800000,m2
0.800000,whistle
0.800000,train
0.800000,wheel
0.000000,airraid
0.000000,warning
0.800000,reng
0.800000,rstart
0.800000,rstop
0.800000,
0.800000,reng
0.800000,rstart
0.800000,rstop
0.800000,scrape
0.800000,Slat
0.800000,debris
0.800000,gveng
0.800000,gvstart
0.800000,gvstop
0.800000,gveng
0.800000,gvstart
0.800000,gvstop
0.800000,wheel
0.800000,buffet
0.600000,tmusic
0.800000,explode1