Before copying Firefox Profile Data please ensure that firefox is closed
To copy all Firefox profile information across from one User in Windows to another user:
Step 1
Reveal Hidden Files and Folders (opens in new tab)
Step 2
Open Windows Explorer
Step 3
Browse to the Firefox Profile Folder of the old user. The path is:
C:\Users\<Windows login/user name>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile folder>
Where <Windows login/user name> is the old username
Step 4 – Copy all the files in the profile folder
Press CTRL + A and then CTRL + C
Step 5
Browse to the Firefox Profile Folder of the new user. The path is:
C:\Users\<Windows login/user name>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile folder>
Where <Windows login/user name> is the new username
Step 6
Press CTRL + V and accept any messages asking to override / merge
NOTE: If you can’t find any reference to Mozilla, Firefox or profiles in the AppData\Roaming folder of the new user this will be most likely because firefox hasn’t been opened up yet under the new user’s account. Once you open up Firefox completely once this folder will be created.