Items in notepad resorted by date and time the item was created.

 
 I'm posting 3 messages separately so each subject line concerns only one item that will come up in a search if someone else has this issue.
 

 How the heck did the items in one of my notepads resort themselves by the date and time of day the item was created?  I'm not aware of anything I did to cause this. Didn't even know such a sort was possible. Can anyone enlighten me? How can I unsort this back to the original order?
 

 I was taking notes from a book starting from page one and so on. I want the items to be in order as I enter them.  I took some notes say on Monday, came back Wednesday to do the rest and also inserted a note from an earlier page that I had skipped.
 

 Then I left that notepad and when I came back to it all the items had resorted by the date and time of day they were created. So the last item I created on Wednesday (the item I inserted) was now the first item in the Notepad followed by all Wednesday's other items in reverse order as created, followed by Monday's items in reverse order. In other words, the very first item I created on Monday was not the last item in the Notepad.
 

 Any suggestions?  Thanks much.