My kindle paperwhite is approx a year old and I do not like the new update especially where the bookmark is concerned!
In fact there is no bookmark at all,I've been in touch with "support" who told me to factory reset it and it "should" return, it doesn't and I've reset it 3 times now! The only way to bookmark it is to get the Android Kindle app ,find the book,page and bookmark that then sync the kindle and it sometimes appears!
I don't think they should meddle with things that work ok , "if it's not broken then don't fix it " .