Account Notes lets you add notes to any account, view all notes associated with a particular account, and see the user who added each note along with its timestamp.
Adding and viewing account notes
To add a new note or view existing notes for an account:
Go to Manage in the top menu.
Click on an account from the list.
Select Account Settings on the top right of the page.
In the toolbar (under the metrics row), click the Account Notes icon (pencil inside a square).
Type a new note.
Click the Save icon to the right of the note.
When you've finished inputting your note(s) and viewing existing ones, click the X to return to account settings.
Notes are automatically saved with timestamps and the author's name. You can edit or delete notes you created by clicking the pencil icon next to them.