>In Firefox-based browsers, the option controlling the user agent is
"general.useragent.override".
Variable: /// Value:
general.useragent.override /// Mozilla/5.0 (Windows NT 6.1; rv:45.0)
Gecko/20100101 Firefox/45.0
general.appname.override /// Netscape
general.appversion.override /// 5.0 (Windows)
general.oscpu.override /// Windows NT 6.1
general.platform.override /// Win32
general.productSub.override /// 20100101
general.buildID.override /// 0
general.useragent.vendor /// [enter variable - but leave value blank]
general.useragent.vendorSub /// [enter variable - but leave value blank]
intl.accept_languages /// en-us,en;q=0.5
network.http.accept.default ///
text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
network.http.accept-encoding /// gzip, deflate
-----
Notice however that standard Firefox has become very good at defeating
fingerprinting, so you can just keep that one as it is and disable javashit
and be good.
