If you have selected to load the ski pass to a registered Snowitcard , you will see the number of the card.
If that Snowitcard has not gone through the turnstile yet, you will be able to change it.
To do so click edit.
A new table will open where you need to enter the new Snowitcard number and click apply changes
Wait for the changes to load, in the next step you will need to confirm the changes.