On the Notes tab of the file properties you can change the notes which you want to store for your database and for the master password.
Comment: You may edit the comment on the database in this field.
Both notes will be shown in the dialog for entering your master password when you open a file.
NOTE: Into these two fields, do not enter any information which could help a third person to guess or even find out your master password. If you enter a hint, it should merely serve as a reminder for you alone and nobody else.