(Just realized I didn't reply to the whole group when I replied a few weeks ago; posting again here for future reference.)
Hi,
Thanks for the report! That's quite odd. I don't see a similar problem on Firefox for Mac -- maybe someone else with Ubuntu could confirm this behavior? At least on Mac, I can reach the preferences via the "Preferences" button in the add-on list; it should be the top option. (Make sure you have the latest version of ShareMeNot -- currently 2.2.)
You can manually change the config value in the following way, but please be careful not to accidentally change other non-ShareMeNot-related config values -- proceed at your own risk.
1. Go to about:config
2. (Click "I'll be careful, I promise" if you've never been here before. If you don't see this, skip to step 3.)
3. Search for "sharemenot"
4. Right click on the line for "extensions.
sharemenot@
franziroesner.com.replaceButtons" and select "Toggle"
Hope that helps!
Franzi