Hello Yosh!
This feature was implemented in the Report Editor.
Here it is step-by-step explanations with screenshot:
1) Search Tool report for Store Manager for PrestaShop -
http://screencast.com/t/Ie5PsdnXUfq7
2) Select Tool report -
http://screencast.com/t/s0j5VQNKy
3) Open Invoice Report via Editor -
http://screencast.com/t/5Oc4Vh3cv
4) You can edit file as you wish
5) Don't forget to save changes after manipulations. :-)