Nog Dog is correct, the collections is another way to sort the kindle. You can still coose to see all your books by title or author or recent first. But if you like collections, then that is the way you would leave it.
I have
"Kindle library" (all my books are in this collection and I read the book from this folder so it always stays on top
My Books - (this is the calibre catalog, but at the moment the catalog wont go into any collection so it is empty)
Modern quality fiction
Historical and ancient fiction
Light fiction
Holiday Reads
Non Fiction
Series
Classics
Mystery and Thriller
Quality General Fiction
Read
"Only when desperate"
Smut
And then an author list (eg JD Robb etc)
(And because it wont go into any collection, the poor calibre catalog is last, unsorted on the last page)