To edit a Task you'll need to expand it by clicking on it.
Once it's expanded you'll be able to change the following details.
Edit the name
To change an item’s name/ title, click on Edit, and the text should become editable. Clicking the Enter/ Return will save the new name.
Assign to a colleague
Click on Assign to a colleague, type the name and then select the member of your team who will be responsible for the item. And yes, you can assign the item to yourself.
Note: you can assign all Tasks to one person in one go.
Edit the due date
Click on the link and select a due date. If no due date is selected, as a default the item will appear in your colleague’s to-do list due on the end date of the Work. If there is no end date, then it will take the start date of the Work. More on due dates here.
Add a description
If you'd like to add more information to an item, adding a description will certainly assist. You can edit this box directly.