Modifying the Session Comment
When a session comment is entered, you have the possibility to enable the autosave feature allowing you to save automatically when leaving an item for example: Note: The session comment can also be entered and remembered from the login dialog:
You can change or remove the session comment by clicking on the comment box in the black bar in the bottom. 
If you remove the comment you will be prompted to enter a comment whenever you want so save a change.