How to change firefox startpage from Ubuntu's to Firefox's=?iso-8859-1?Q?=3F_=96_askubuntu.com?=

How to change firefox startpage from Ubuntu's to Firefox's? – askubuntu.com

Well, I installed Ubuntu GNOME Remix. Now I miss the "Restore Previous
Session" button that Firefox start page has. How do I get it back? This is
what I want: