Click your name in the top right hand side of the screen. You will select "Settings" from the drop down menu.
On the Payment Settings tab you can change the merchant notifications for both successful and failed transactions. You can select to delete an existing email address by clicking on the x in the email field.
In order to add a new email address simply type it into the blank field and then click enter.
*Please note in order to save the new email address properly you must press enter after typing in the complete email. The email will be displayed in green once the email address has been accepted.
The final step is to hit "Save Changes" at the bottom of the page.