You may have a corrupt xulstore.json file.

Type about:support in the address bar and press enter.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the xulstore.json file. Then rename or delete it. Restart Firefox.

If you have made changes to Advanced font size settings like increasing the minimum/default font size then try the Default font size setting "16" and the Minimum font size setting "none" in case the current setting is causing the problem.

• Options/Preferences -> Content : Fonts & Colors -> Advanced -> Minimum Font Size (none)

Make sure you allow pages to choose their own fonts.

• Options/Preferences -> Content : Fonts & Colors -> Advanced: [X] "Allow pages to choose their own fonts, instead of my selections above"

It is better not to increase the minimum font size, but to use an extension to set the default page zoom to prevent issues with text not getting displayed properly.

In case you use "Clear history when Firefox closes" or otherwise clear history.

• do not clear the Cookies
• do not clear the Site Preferences

• Options/Preferences -> Privacy -> Firefox will: "Use custom settings for history": [X] "Clear history when Firefox closes" -> Settings
• https://support.mozilla.org/kb/remove-recent-browsing-search-and-download-history

• clearing "Site Preferences" clears exceptions for cookies, images, pop-up windows, and software installation and exception for password and other website specific data
• clearing cookies will remove all selected cookies including cookies with an "Allow" exception you may want to keep

Fred: the new xulstore.json file gave me firefox without my bookmarks toolbar, and still did not save magnification information. I went back to the previous one.

Cor-el: I've not made any changes to Advanced font size settings. The default size is 16, and pages are allowed to choose their own fonts. I do not clear history.

When I upgraded to 47.0 the other day, I was urged to (and did) disable NoSquint. Before the upgrade, site magnification settings were retained. Afterward, they are not.

Do all zoom prefs have their default value if you check them on the about:config page?

• http://kb.mozillazine.org/Zoom_text_of_web_pages

• http://kb.mozillazine.org/browser.zoom.full
• http://kb.mozillazine.org/browser.zoom.siteSpecific
• http://kb.mozillazine.org/toolkit.zoomManager.zoomValues
• http://kb.mozillazine.org/zoom.minPercent
• http://kb.mozillazine.org/zoom.maxPercent

You can look at NoSquint Plus.

• https://addons.mozilla.org/firefox/addon/nosquint-plus/

browser.zoom.siteSpecific is listed as User specified.

NoSquint is disabled, as per mozilla's urging after upgrade. Browser says it is incompatible with 47.0. You mean try NoSquint PLUS to fix this problem?

If browser.zoom.siteSpecific is user set (false) Firefox won't remember the page zoom on web pages as part of the Site Preferences. You can reset this pref via the right-click context menu to the default value.

Okay. Meanwhile, I've installed NoSquint Plus which appears to be handling things with aplomb, so I guess I'll leave it alone?

I love me some firefox. Nothing else does what FF does!

thanks for your help!

The author of the old NoSquint extension had not updated it since April 2013 so it was bound to break at some point.

Besides the NoSquint Plus extension there is also the PageZoom extension. https://addons.mozilla.org/firefox/addon/pagezoom/

Thanks James. I remember now, the old NoSquint simply disabled user zoom inputs; that's why it had to go. NoSquintPlus leaves the FF toolbar's indicated zoom level at 120%, for some reason, but at least does respond to user inputs and remembers settings, so I'm happy. I don't need to know the % number. The NSP folks are releasing iterations every few days so hopefully they will stay on top of things for awhile.