history record/ back button is required

I am one of the new user of this memo user,. Few days ago, I started to use this app generate my own lecture notes with the lecture notes pdf. After finish editing, I accidentally deleted my notes and those notes could not be recovered as there was no any back button is given, even I can recover it by returning to the history record . I lost all my notes and I feel so panic and dismay as I have got a test for the upcoming week and I have no time to prepare the notes again.For this reason, I would like to request MEMO to develop a back button recover the notes or back to the previous step in order to prevent the lost of notes and data. Thanks.