You can edit categories in Common Tasks by selecting Edit Categories under Settings.
Select category
The displayed category of tasks can be changed with the category selector.
Move task to different category
To permanently move a task to a different category, click the Category field and select the category from the dropdown list.
Move task to new category
To permanently move a task to a new category, click into the Category field and type the name of the new category rather than selecting an existing one from the dropdown list.
Add task to additional category
To add a task to an additional category, first duplicate it using Duplicate Record (the green copy icon). Then, change the category on the new record. You can change the category to an existing or new category following the instructions above.