The Windows 10 upgrade should not affect your Thunderbird or your Firefox accounts or settings.

Just to make you feel better, why not copy both your Thunderbird and your Firefox profiles onto an external drive. (Copy/Paste - not Backup) If you feel that some data has been altered by the upgrade, you can copy and paste the data back into the appropriate profile.

The Windows 10 upgrade did not delete or deactivate any of my programs, including ones that I have had from my XP days, and were re-installed on my Win8 machine several years ago. (I still use Access97 from the Office97 suite.)

I did find that some desktop shortcuts did not work after the upgrade as they pointed to windows system folders that changed names, but the shortcut was not updated. The programs were still installed, and once I re-pointed the shortcut to the executable, everything worked the same as before.

Thanks for the quick reply,

You have made a good suggestion, "Copy and Paste both Thunderbird and Firefox profiles to an external hard drive" Question, where do I find these profiles on my existing hard drives, also I have an SSD drive solely for the Operating System and a regular HD for data and programs, does this make a difference in how I do the copy and paste?

Thanks for the help God bless Fromjim

it depends on if you moved the default locations of Thunderbird and firefoxes profiles.

If they remain in their default locations in appdat.

Type %appdata% in the start menu search box and press enter.

Copy the Thunderbird and the Mozilla folders to your backup device.

If you have changed those defaults, I assume you would know where you placed such data.

This is great, thanks and God bless all .

Fromjim