Queue-callswaiting=silence/1

Dear All,

I am running Asterisk 1.8.9+FreePBX 2.9.0.9.

/etc/asterisk/queues_additional.conf was automatically generated by FreePBX as below.

but why the value queues- options below:

queue-callswaiting=silence/1
queue-thereare=silence/1
queue-youarenext=silence/1

are silence/1 ?

where should I change it? since queues_additional.conf always overwritten by FreePBX? … is there any GUI option in FreePBX for doing this?

[1]
announce-frequency=0
announce-holdtime=no
announce-position=no
autofill=yes
eventmemberstatus=no
eventwhencalled=no
joinempty=yes
leavewhenempty=no
maxlen=0
memberdelay=0
penaltymemberslimit=0
periodic-announce-frequency=0
queue-callswaiting=silence/1
queue-thereare=silence/1
queue-youarenext=silence/1
reportholdtime=no
retry=5
ringinuse=yes
servicelevel=60
strategy=ringall