Hello JDnHuntsvilleAL,

Would you do this please :

Type in the address bar about:config and press Enter (promise to be careful, if asked)

Type in the search bar and look for the preference :

privacy.resistFingerprinting

If the value is set to "true", then change it to false.

In case you had to change the value, then close and restart Firefox.

Also see : https://www.ghacks.net/2019/04/24/firefox-not-remembering-the-last-window-size-this-may-fix-it/

Does that work for you ?

Thanks. I figured there was something in about:config, but didn't know what it was called. I'll let you know if it appears to have fixed my problem - sometimes just closing and opening Firefox didn't cause the problem. I'm going to do a complete reboot to see if that does anything.

No, that didn't do it, nor did the tip in the article you referenced.

HOWEVER, I may have found the problem. While in about:config I decided to see what I could find. I did a search for "size" and found:

browser.cache.disk.smart_size.enabled

It had been modified, so I right-clicked on it and set it to DEFAULT. That seems to have done it.

Thanks for the quick response.

Good for you to have figured it out - well done !

Would you be so kind as to mark your own (last) post as Chosen Solution ? ("Solved the problem" button to the right of your last post )

Weird. browser.cache.disk.smart_size.enabled is about the size of the disk cache (automatic disk cache management) and normally wouldn't have effect on the Firefox window dimensions.

This could possibly have be a problem with xulstore.json in the profile folder that got fixed automatically.

It didn't. I was wrong. Back to the original problem PLUS. In trying to fix ANOTHER problem with Nextdoor.com, I cleared the cache. Now I'm finding old problems are back, such as TVGuide.com not saving my "favorites" again. I may give up on Firefox after all these years and start using (ugh) Chrome.

A detail like a website remembering you is stored in a cookie.

You can use these steps to make a website recognize and remember you:

• you can create an Allow exception to keep specific cookies, especially in case of secure websites and when cookies expire when Firefox is closed.
• Options/Preferences -> Privacy & Security
  Cookies and Site Data: Exceptions

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 & 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

Try to rename/remove xulstore.json and when present delete localstore.rdf in the Firefox profile folder with Firefox closed.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Thanks, but that's not it. I asked this question once before and the answer then was to delete the history for a single web site.

https://support.mozilla.org/en-US/questions/1254619

Did that again, now to tvguide.com to see if it worked again.

DAMNIT, no. I am again having problems. Like I said, I think the real solution is to DUMP FIREFOX. It USE to be such a good browser, but the developers couldn't leave well enough alone.

UPDATE: Not only did I still the sizing problem, but I started running into other problems. First I started having problems with AdBlock Plus. The "Installation Successful" page started coming up in a second tab every time I started Firefox. I went through their instructions several times, but nothing changed. During this, I noticed that changes to ABP options didn't seem to hold. Also, elements I had deleted before were appearing again, and re-deleting them only worked if I didn't close Firefox.

Ran into another problem with Firefox options that made me believe that somewhere, somehow, the files necessary for the changes were in a "Read Only" mode or something. None of the changes I was making was holding. Trying to change permissions via Windows File Explorer didn't work.

My solution, which seems to be working, was to completely uninstall Firefox. After that I used File Explorer and deleted all the Mozilla folders in Program Files, Program Data, and the various AppData folders. I rebooted, brought up my (ugh) Chrome browser and downloaded an new copy of Firefox install from Mozilla.org.

So far I've only re-added the ABP add-on and the "Turn the Page" theme, but everything seems stable again. If anything changes I'll post another update.