I can't find /tmp/something/session.conf.
You have to tell Geany to use the alternative config by starting from the command line with the `-c /tmp/something` . I picked `/tmp/something` because it is unlikely to exist so no other settings get in the way and Geany will create it with default values then it gets deleted automagically when the machine is shutdown.
If it happens again look for `session.conf` in whatever config you are using, default `your home directory/.config/geany`