You have to do that yourself. This article may help.

https://support.mozilla.org/en-US/kb/wrong-home-page-opens-when-i-start-firefox-how-fix

See also:

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

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or if userChrome.css/userContent.css is causing the problem.

• switch to the Default System theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

If you want to restore your previous homepage on Firefox, you can follow these steps:

Open Firefox and click on the three horizontal lines in the upper right corner to open the menu.

Click on "Options" or "Preferences" depending on whether you're using Windows or Mac.

Click on "Home" in the left-hand menu.

Under "Homepage and new windows", select the "Custom URLs" option.

In the "Custom URLs" field, enter the URL of the website you want to set as your homepage.

Click on "Use Current Pages" if you want to set all currently open tabs as your homepage.

Close the options window to save your changes.

Once you've completed these steps, your previous homepage should be restored in Firefox. If you continue to experience problems, you can try resetting your Firefox settings to their default values. To do this, click on "Troubleshooting Information" in the "Help" menu, and then click on the "Refresh Firefox" button.