Gain setting 978 uat

I am running the latest ads-b buster bin with duel sdr's and trying to set the gain on the 978 UAT sdr is there a setting somewhere to set the second sdr or is it automatic

 

36 normally .. maybe 42

/etc/default/dump978-fa

 

Where do you change this in the image or can you change it in the terminal

 

36 normally .. maybe 42

/etc/default/dump978-fa

 

I cannot find that anywhere in the image and when I use the command line it just says no such command

 

The file to edit is

/etc/default/dump978-fa

thus

sudo nano /etc/default/dump978-fa