For a Geany built from git on LM I get "sensible-browser" in the preference. So its probably not Ubuntu, somehow Geany build selects that value, but I ran out of time to find how/where.
Hmmm, no actual solution, but I ran the built from git Geany with a non-existant config dir, and it switched the settings back to usual defaults:
`x-terminal-emulator` -> `xterm` `sensible-browser` -> `firefox`
and now `Help` runs firefox but does not work because I didn't build the local doco so its looking for `https://www.geany.org/manual/1.39/index.html%60 which of course does not exist. @ntrel Is that your problem?
As to how the setting values above got into the local config `~/git-geany/config` from the default config `~/.config/geany` I don't know. Maybe a GP plugin does something wrong, will check later.