I guess you have already found out a solution to this, but it is worth repeating.
When configuring your empty book list, first create all collections, and create some additional ones with generic names just in case - the names can always be changed later on in the Collections view.
Import your files or folders. The first time, when the book collection is empty, all chosen books appear, and you then select all of them and assign them to your collection of choice.
However, when importing more books, remember to first select ALL books that have previously been imported, and are already displayed in the software, and add your additional files or folders. The new books appear at the top, and they are not selected by default, which makes it easy to toggle the selection, and assign them to the collection of your choice.
The software that is included with the PRS-T1 leaves a lot to be desired, which I guess all of you have noticed.
In fact, I have never during my career as a software developer for almost 20 years now stumbled upon a piece of software that is so crude and contraproductive, which says a lot about the software being delivered.
However, The reader PRS-T1 in itself is very good, and has provided me with lots of productive hours reading through material (PDF files) that you normally don't want to read on your computer, like PDF files being several hundred pages long. You just get tired reading them on screen along the way.
