If you use coolreader, when you open book first time, it is added to recent book list. But when you open it second time, the book isn't placed as first in the list.
coolreader has its own recent list - the book you read is placed as first in it, but the Onyx's list is commonly used for open a book.
If you use fbreader, the book you read is placed as first.
This bug of coolreader is old.