Firefox remembers zoom settings for each site that you visit. With the site on display, you can page zoom by using the keyboard short Control+0 (zero)

For more details on page zoom see https://support.mozilla.com/kb/Page+Zoom

Yes, thank you. Now if they'll just get back the NIS toolbar and make it compatible with NIS settings all will be well with this part of the world :)

It is up to Norton to make their toolbar work. They have a history of being slow when it comes to updating their software to work with new versions of Firefox. They have indicated for Norton 360 they will release an update in early May, I do not know about the timescale for other Norton products.