The "default browser" is the one that Windows will use to open links from other applications, or desktop shortcuts. Whether a browser is designated as the default doesn't affect how web pages work ''inside'' the browser. Sites generally recognize that you're still logged in by setting a cookie. When you first install Firefox, it is configured to accept and retain these cookies. However, there are many ways for cookies to get cleared, including: * Settings on the Privacy tab of the Options dialog such as whether to accept cookies and how long they are kept - [[Settings for privacy, browsing history and do-not-track]] * Optional clearing of history at shutdown (although the feature is called clearing history, there are some 10 or more categories of data you can individually choose to clear or keep) * Using the private browsing feature - cookies last only as long as the private session * Privacy-related add-ons that change how cookies are managed -- your system data doesn't show any of these * External security, privacy or system cleaning software In your case, your "More System Details" shows that you have Firefox set to start automatically in private browsing mode. In this configuration, Firefox doesn't keep any cookies between sessions, so as far as websites are concerned, the next time you visit you're a stranger. One way this could have been set is if you or someone else with access to your computer went into the Privacy Options and set Firefox to "Never remember history". You'll probably need to turn off automatic private browsing, unless you can find an add-on to store cookies you want to store between private sessions.