Hi Alex, what are your current settings under Privacy Preferences? You can check here:

"3-bar" menu button (or Firefox menu) > Preferences

In the left column, click Privacy. On the right side, if you see "Firefox will: Remember history" please change that to "Firefox will: Use custom settings for history".

The defaults are:

[X] Accept cookies from sites Accept third-party cookies: Always Keep until: They expire (I close Firefox also should work fine)

Regarding local storage, could you check whether the following preference has its default value:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste stora and pause while the list is filtered

(3) If the dom.storage.enabled preference is bolded and "user set" to false, double-click it to restore the default value of true

Any changes so far?

Thank you for trying to help so promptly.

My privacy settings are as you suggested: Accept all cookies, Keep until they expire.

With local storage, the dom.storage.enabled status is default, value is true.

Any other ideas?!

Some add-ons may modify how cookies and local storage work. Could you test in Firefox's Safe Mode? In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the option key when starting Firefox. (On Windows, hold down the Shift key)

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement? (More info: Diagnose Firefox issues using Troubleshoot Mode)