1) Click on the cog icon to access the menu.
2) Click on Contact Details to access your settings.
3) Scroll down until you see the section on Notifications.
4) The ToDo column allows you to select the events on a form (where you have been added as a collaborator) that will trigger a notification being sent to you in iTWOcx. If you don't want to receive notifications for a particular event then remove the tick by clicking on it.
For more information on events that trigger notifications refer to What are iTWOcx Notifications.
For information on the Email and Preview Email columns refer to How to change Email and Preview Notification settings.
Don't forget to save your changes by clicking save in the bottom right hand corner.