Windows
通常，你能通过“工具 -> 选项 -> 常规 -> 默认浏览器 -> 检查”来设置Firefox为默认浏览器。如果不行，您有两个选择。
强制Firefox自动设置
如果Firefox已经认为自己是默认浏览器，那么它就不再弹出默认浏览器提示了。通过“开始 -> 运行”，然后把下面的命令行输入文本框。
firefox.exe -silent -nosplash -setDefaultBrowser
手动设置
* Windows XP 中， “开始 -> 控制面板 -> 添加/删除程序 -> 设置程序访问和默认值(左边)-> 自定义” 设置 Mozilla 或者 Mozilla Firefox为你的默认浏览器。
如果上面的办法无效，那么请照以下设置。
* Windows 中，“开始 -> 控制面板 -> 文件夹选项 -> 文件类型” 把下面的文件类型分配到Mozilla 或者 Mozilla Firefox。
o URL:超文本传送协议
o URL:带私人验证的超文本传送协议
o URL:文件传送协议
o HTML 文件
o HTM 文件 (可选)
Note: you may find the URL file types above under extension "N/A" or "(none)".
* In Windows XP, you must go Start -> Control Panel first.
o If your Control Panel choose "Category View", and click on "Performance and Maintenance". Then, click on "Files Types" in the left column under the heading "See Also".
o If your Control Panel uses Classic View, then go Folder Options -> File Types.
o In either case, set the above to Mozilla.
第三方工具
There is a freeware utility that will save you a lot of work (see second route) by, in general, automating the steps for you [1] (http://www.pc-/win32/freeware/setbrowser/). But if that doesn't work, follow instructions below.
Linux
You may have to change both Gnome and KDE config (see below). If you want the URLs to open in a new tab instead of the last tab opened, use this workaround :
* Edit the "firefox" startup script in the firefox base directory
* Search for a line containing "openURL"
* Replace _remote_cmd="openURL(${_optLast})" with _remote_cmd="openURL(${_optLast},new-tab)"
You can replace "new-tab" with "new-window" if you want to open the URLs in a new window
Gnome
* 到 “应用程序 -> 桌面首选项 -> 高级 -> 首选应用程序。
* 选择”Web 浏览器“，然后键入“firefox %s”(mozilla则键入 "mozilla %s")。注意“firefox”或者“mozilla”的符号链接必须放在某个默认路径(PATH)下(例如，通常把"firefox"的符号链接放到 "/usr/bin/").
KDE
* Open kcontrol (KDE configuration center)
* Select components -> components chooser
* Open the "web browser" component
* Check "the following browser" and type in "firefox" (or the name of your firefox startup command)
If you don't notice the "web browser" component :
* Select components -> file association
* Select text -> html in the MIME type tree.
* Select "Add..." under "Application Preference Order".
* Write the command "firefox %U" and press ok (you need "%U" so you can load URLs that are non-local files)
Mac OS X
1. Download Safari (/safari/) if you do not already have it. 2. In Safari, choose "Preferences" from the menu. 3. Click the "General" icon, and choose Mozilla from the default web browser pop-up menu. If you dont see Mozilla in the list, make sure it is in the "Applications" folder.
