Remove Norton Safe Search from new tabs in Firefox

Norton 360 for Mac
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I am trying to restore my original home page in new tabs in Firefox using the following procedure in Norton Support.  However there is no "browser.newtab.url" line in the about:config page.  Any advice?

Thanks

How do I stop the Norton Home Page from loading in new tabs?

  1. In the address box, type about:config.

  2. In the page that appears, click I'll be careful, I promise.

  3. In the search box, type newtab.

  4. In the browser.newtab.url row, right-click the current URL value and click Modify.

  5. In the Enter string value dialog, type the URL that you prefer.

    <p><strong>If you prefer not to keep any specific page, type <span>about:blank</span>.</strong></p>
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<p><strong>Click <span>OK</span>.</strong></p>
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