Note that syncing history is rather limited.

• Synced history expires in 60 days.
• New history is only uploaded for the last 30 days.

You can possibly use a removable USB drive to transfer data directly since both devices as desktop devices (not mobile).

You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data. Note that best is to avoid copying a full profile folder.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

• bookmarks and history: places.sqlite
• favicons: favicons.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (encrypted logins;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
  key3.db support ended in 73+; to use key3.db in 58-72, make sure to remove key4.db
• cert9.db (58+) for (intermediate) certificates stored in the Certificate Manager
• persdict.dat for words added to the spell checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

thanks! it partially(?) answered my question to you, but my original question was, getting an 2f/(f.f.)a e-mail code in my gmail inbox so i can just/only transfer mozilla firefox's browsing history to those websites i visited, from my windows 10 desktop pc-which is very slow(!)-to my newer windows 7 laptop pc-which is much faster and isn't bloated with junk-can i still/how can i use the 2fa e-mail(6 number) code to commence with my firefox browsing history transfer here from one/the old desktop pc-windows 10-to the new computer-the laptop pc-windows 7? i commented about it earlier today regarding this! thank you and have a good day there! thanks, mike k.

i tried the flash-drive route, but it was too tedious, time-consuming and quite confusing to me to do all of it! thanks! mike

[Personal information removed by moderator. Please read Mozilla Support rules and guidelines, thanks.]

You can only use 2FA via an app on a mobile device or alternatively via an authenticator (TOTP) extension in Firefox, but not via email.

• https://addons.mozilla.org/en-US/firefox/search/?type=extension&q=authenticator

Note that you only need to copy places.sqlite from one device to anther device to transfer the history and the bookmarks (both are stored in places.sqlite). Only if you want to transfer more data then you need to copy other files.