Please read this article.

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles#w_restoring-to-a-different-location

Please let us know if You need any help.

Hello, you can also try to modify profiles.ini file to point to the new location.....mmm.......it is more complicated !

see : Modify profiles.ini to point to the new location - Advanced

thank you

You can't change that default location.
Firefox will at least create the profiles.ini file to register the profiles.
You can use the Profile Manager to create a new profile and click the Choose Folder button to specify the location of the profile.
Be sure to specify a new and empty folder if you use this and not one that already has files.

The only way to bypass using this location completely is to use a desktop shortcut that specifies the absolute profile path.

• https://developer.mozilla.org/en/Command_Line_Options