You can go to the pages for the individual slips and change what you need to there. 

To get to the T-slips:

1. In the upper-right corner of your screen, select Find (magnifying glass 🔍).

2. In the Find window, type “t-slips”, select it from the list and click Go.

3. On the Income Slips/Entering your federal T-slips page, make sure the slip you need is checked off and click Continue until you get to that page.