That means a malware or something changed it from what it was before and for that to happen is one malware infection or a software you installed changed the homepage from your default. You can change it in your options settings but if that doesn't work it means that was installed by a software and any attempts to change won't work unless you find the offending program and uninstall it so it defaults back to your default homepage.

Hi,

That search.searchedd.com is a browser hijacker - malware that you will of course want to get rid of.

Go to the 3-bar menu (or 'Tools') => Addons => Extensions and look for any unfamiliar or suspicious looking extensions.

When you find any : remove them.

Do the same in your system's Control Panel.

However : most malware will be 'hiding' somewhere , so let's run malware scans :

Further information can be found in this article : https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed malware scanners. They all work differently - what one program doesn't pick up, the other might.

Also see : https://malwaretips.com/blogs/remove-search-searchedd-com/

This should help you get rid of the nuisance .....