Click the "Tools" menu at the top of the Netscape Navigator window and click "Options."
Netscape Navigator is a Web browser for Microsoft Windows, Mac OS X and Linux. Official support for Netscape Navigator ended on March 1, 2008, but it still functions. You can make Netscape Navigator your default Web browser from its Options window. After you make Netscape Navigator your default browser, links from other programs in Windows open in Netscape Navigator instead of another Web browser.
Click the "Main" icon at the upper left corner of the Options window.
Click "Check Now" under "System Defaults" at the bottom of the main pane.
Click "Yes" to make Netscape Navigator your default browser.
Click "OK" at the bottom of the Options window.