Extensions I have installed:

• CanvasBlocker
• DecentralEyes
• Disconnect
• HTTPS Everywhere
• Privacy Badger
• uBlock origin

However, disabling all extensions does not help.

You can rename (or delete) the content-prefs.sqlite file in the Firefox profile folder to reset the page zoom for all websites.

Type about:support<enter> in the address bar.

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 above file. Then rename or delete it. Restart Firefox.

FredMcD said

You can rename (or delete) the content-prefs.sqlite file in the Firefox profile folder to reset the page zoom for all websites. Type about:support<enter> in the address bar. 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 above file. Then rename or delete it. Restart Firefox.

Hi FredMcD. Thank you for your help. I tried the above steps couple of times. Once with extensions and addons enabled, once with extensions and addons disabled, once in safe mode. Every time i renamed content-prefs.sqlite file in my profile folder. However, FF still does not remember page zoom.

E.g. I navigate to https://en.wikipedia.org/wiki/Main_Page . Once the page loads, I set zoom to 150% (Ctrl + mouse wheel). Then I close this tab. When I open new tab and navigate to the same page, page zoom is reset back to 100%. When I tried this on my other computers, this worked as supposed (web page in new tab opened with 150% zoom). I will try to install fresh debian on a new computer and try to see if I can replicate this problem on fresh debian install.

So I installed fresh debian in new virtual machine. Zoom level is remembered correctly, so the problem is specific to my setup, I guess. Any idea what might be causing this?

I don't know Linux so check with its support.

That was very good work. Well done. Please flag your last post as Solved Problem so others will know.

Make sure you do not run Firefox in permanent Private Browsing mode (Always use Private Browsing mode; Never Remember History).

• https://support.mozilla.org/en-US/kb/private-browsing-use-firefox-without-history

• Options/Preferences -> Privacy & Security
  Firefox will: "Use custom settings for history"
• remove checkmark: [ ] "Always use Private Browsing mode"

You can check this pref on the about:config page to see if resist fingerprinting (RFP) is enabled and if this pref is user set (bold) reset to false via the right-click context menu.

• privacy.resistFingerprinting = false

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

• do not clear the Site Preferences

• Options/Preferences -> Privacy & Security
  Firefox will: "Use custom settings for history":
  [X] "Clear history when Firefox closes" -> Settings
• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

• 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

Hey cor-el, thank you for your help. privacy.resistFingerprinting = true is causing this. Turning this off solves the issue of page zoom. Thank you once more.

I checked and privacy.resistFingerprinting=false is OK in my config. I also have under History:

Firefox will "Use custom settings for history" [ ] Always use private browsing mode (unchecked)

    [x]  Remember browsing and download history
    [x]  Remember search and form history
    [  ]  Clear history when Firefox closes (unchecked)

Yet, Firefox does not remember any page zooms.

I would like to permanently set ALL page zooms to 133%.

Currently using Firefox Quantum, 68.0.2 (64 bit)

Please help.

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

• do not clear the Site Preferences

• Options/Preferences -> Privacy & Security
  Firefox will: "Use custom settings for history":
  [X] "Clear history when Firefox closes" -> Settings
• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

• 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, use this instead:
  use Options/Preferences -> Privacy & Security
  Cookies and Site Data: [ ] "Delete cookies and site data when Firefox is closed"