Visitor fields are set per button. This means you can set up different fields for different types of visitors, based on their button selection! Collecting information from visitors is available for Check-In and Notification buttons. Delivery and Check Out buttons don't collect information from visitors.
Start on your buttons tab on the left of your account dashboard. Select 'Existing Buttons' on the right then click to edit (or add a new one) then scroll down to the Visitor Fields section. You'll see you can 'Add a Field', or you can edit the fields automatically added to each button.
You'll see that there are a few customization options. The first line "Hi There, what's your full name?" will appear with the field for visitors to see. The second line, "Type your full name" actually appears IN the field to prompt visitors as they begin typing. Both of these labels can be customized, allowing you to create the field of your dreams... License Number, Super Hero, Favorite Color.
Finally, you'll see that on the left you can drag and drop your fields into whatever order you would like. And the little lock icon allows you to choose whether or not the field is required (please note the 'optional' setting is not currently available for yes/no field type).
You can view all information collected from your visitors via the Visitor Log. Name and company are immediately apparent. Additional fields can be seen by clicking anywhere on the line of that visitor; this will open the visitor's details including additional fields, NDA signature, etc...
Visitors will see each field, one at a time.