How can I go back to the previous version? I can't find anything on addons.mozilla org. Apparently 18.0 has been removed in the meantime, but I would like to prevent uninstalling and re-installing again, as my configuration might get lost. Is there any other/better way?

EDIT: As I didn't want to uninstall and re-install an older version again (because of loss of the configuration), I did just wait and now installed 18.1 - this now seems to work again.

But as other users already stated, this is poor testing before releasing an update. I mean, the general default zoom for all sites is the main function of this add-on (at least for me), and if even that doesn't work, it's completely useless.