Configuring x-www-browser
in Alternatives, XDG’s default-web-browser
and Lubuntu’s default internet browser application in Session Settings is not enough. Turns out Chrome looks at /etc/xdg/xdg-Lubuntu/mimeapps.list
and you have to edit it as sudo and replace the instances of the “firefox” string with your browser of choice.
Hope I’ve been of some help.