Rename groups in pivot table

In my pivot table the 1st column is made up of a bunch of categories. I've selected and grouped them in the way that I want. EX: category (row) 5, 6, 7 grouped. Category(row) 9, 12, 13, 15 grouped.

Each group however is automatically named :Group1, Group2, group3.. etc

How can I edit the names of these groups to something descriptive of what they are grouping?

you should be able to highlight them and just overtype them..