Hi There. I am Bing and I look forward to helping you with your issue today.
So basically your question is how to restore your Thunderbird data from an old copy of Windows 10 to a new one? Is it correct?
> I have a new copy of Thunderbird. I have to direct it to my old copy of the data. What is that called?
It is called Import, in Mozilla's terminology. They have a knowledge base article for this. Please read and confirm if it is something you want to do.
> No, I don't want to spend yet another $39.00.
I don't know where your $39 topic is from. What I know is you are paying $42 for this Q&A conversation. In my understanding you are a reasonably experienced user, with our Q&A assistance and reading related technical resources, you should be able fix this issue. I don't there is a need for remote assistance, which is normally priced at $39.