Update: It seems last update solved the issue. I use Firefox 59 in Void Linux 32-bit. Every time I open Firefox my search preferences are resetted. I want to use DuckDuckGo as my default search engine, and I change the corresponding setting, but every time I re-open Firefox I find Google is once again my default search engine. Also, if I delete a search engine in my list of search engines, or add a new search engine, or modify it in some way; the next time I open Firefox they come back to the original default settings. It doesn't seem to be a problem of permissions. The ~/.mozilla folder has read, write and execute permissions. I can change other settings, like the homepage, and they stick after re-starting. I tried using Firefox with a brand new profile with no addons, removing the ~/.mozilla folder, but the problem remains. I also removed the ~/.cache/mozilla directory, all in vain. I also tried modifying values in about:config, setting browser.search.defaultenginename to DuckDuckGo. I also modified the value in browser.search.defaultenginename.US to data:text/plain,browser.search.defaultenginename.US=DuckDuckGo It didn't work. I asked about the problem in the appropriate Linux forum, they gave me different suggestions, but no one worked. Finally I tried the Beta version of Firefox 60. It solves the issue, but another bug is introduced, so in the end I gain nothing changing to a less stable version.