Check the Home Page settings: https://support.mozilla.org/en-US/kb/how-to-set-the-home-page

Start Firefox using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

You can also middle-click the Home icon on toolbar to open the custom url homepage in a new tab.

What is the current startup setting ?

You can check that these pages aren't set as multiple homepages.

You can check the homepage setting.

• Settings -> Home
• https://support.mozilla.org/en-US/kb/how-to-set-the-home-page

Firefox supports multiple homepages separated by '|' (pipe) symbols.

All of these comments are missing the point. There is nothing broken here. I am complaining about the fact that Firefox finds it necessary to cram all the "what's new" features in my face when I open up Firefox. To me, the point of setting a home page is so that it is the first tab that I see when I open Firefox. If Firefox wants to open a half dozen other tabs for god knows what, go for it. But DO NOT present me with anything other than my home page first. I will navigate or close tabs as I see fit. But again, when I open Firefox, the ONLY tab I want to see loaded on the screen, is my homepage.

There are times when Mozilla sends out information. When this happens the browser will show the message. After, it should remember you have seen that message and not show it again. But sometimes the browser is not permitted to remember this.

https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

Macs: Make sure you install Firefox properly and that you do not run Firefox from within the DMG (Disk Images) file. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac