There isn't a config file in Extension. You could change engine lists in Search Option in Firefox if you want. In case you want to deploy your Firefox using config files. You should have a look at Firefox enterprise group policy.

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Search engine's url could not be configured there. The only way you can do is install another search engine and remove the current one. By doing this, you need to find a open search xml for that search engine and install it. Some other tools / website may help you do this. But this may be out of scope of this extension.

点 Remove 删掉就不会出现了。你要的功能受浏览器功能的限制目前无法支持。可以考虑换一个插件。

This extension use your search engine list in Firefox settings. (So you do not need to config it, just use it out of box) You may want to change the list in Firefox options: Click three bar icon -> Options -> Search -> One-Click Search Engines. This extension will not come up with its own search engine list (otherwise user has to maintain two search engine lists in both extension and browser, which most users don't like).

Relay on the default behavior cause more problems than its benefit. This extension will no long follow that about:config settings since this version. But we are considering adding a separated options page later if it is needed.