See How to fix preferences that won't save

I've tried each one and nothing worked

I'm not sure what you are doing.

Do you mean what opens when you start Firefox or also when you open a new window when Firefox is already open?

The home page is opened in a new window by default

Is this a problem with the home page setting?

• Tools > Options > General > Startup: Home page

Make sure that Firefox closes properly, see also:

• "Hang at exit": http://kb.mozillazine.org/Firefox_hangs
• "Firefox hangs when you quit it": https://support.mozilla.org/kb/Firefox+hangs

Use "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit) to close Firefox if you are currently doing that by clicking the close X on the Firefox title bar.

I mean when I exit firefox completely and restart it. Just tried closing Firefox with the exit button and that doesn't fix it

You can check if you have a user.js file in the profile folder to initialize some prefs on each start of Firefox.

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

Note that Windows hides some file extensions by default. Among them are .html and .ini and .js and .txt, so you may only see a name user without file extension. You can see the real file extension (type) if you open the Properties of the file via the right-click context menu.

The user.js file is only present if you or other software has created it, so normally it wouldn't be there. you can check its content with a plain text editor if you didn't create this file yourself.

The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.

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