Customize - Field Buttons Missing

Hello,

I'm trying to manage the behavior of breadcrumbs. I found https://www.gpsoft.com.au/help/opus11/index.html#!documents/Breadcrumbs_Configuration.htm which seemed simple enough. However, after I open up the customize menu I don't have any field buttons and I'm confused where to go from here.

How do I get the field buttons to show up? Thanks for your help.

Those are only editable in Opus Pro. Light has very limited toolbar editing, where you can create extra custom buttons but can't modify the main/default toolbars.