- Open Firefox.
- At the top of the Firefox window, click on the Tools menu, and select Options….
- Select the Advanced panel, then click the General tab, and then click Check Now.
- Select Yes to set Firefox as your default browser.
- If Firefox still isn’t the default browser, see Setting Firefox as the default browser does not work.
To change Firefox to no longer be the default browser, you’ll have to set another browser to be the default. This can be done by using the settings in the browser you now wish to be your default.