Well, I just found the solution in the Fine FineReader manual.
It's called "Modèle de zone" in French and I successfully used it to "read" a document (all pages selected). We select it from menu "zone"
I am now like you, when I open a document (image PDF), he begins to numerize
and read it. Up to now, I have no other solution than to accept this behaviour.
Once finished, instead of saving, I just load the area template (file with blk), make sure all the pages of the document are selected, and than order again "read"...
After that, I can save much improved results...
It could have saved me some hours...a few days ago...