The reason I want to copy 'My Documents' is because the J (1TB)
version is up to date and the C(2TB) version is out of date.

I was successful some moving folders/files but I thought it would
be much better to just copy the entire 'My Documents' versus trying
to remember all the files.

So would it be alright to delete 'My Documents' on the C(2TB)
so I can replace it with the 'My Documents' from J(1TB)? If so
then I can proceed with switching the HD's and reinstalling FF

https://www.mozilla.org/en-US/firefox/new/

and hopefully everything will return as before and I will check
the 2TB in the enclosure.

Robert