AirBNB Custom Link Settings in OwnerRez

Hello, I am on API to AirBNB. Where do I set the custom links? I have them set for several properties, but not my newer listings.

It is not possible to create custom URLs on Airbnb from OwnerRez - that can only be done in Airbnb itself.

https://www.ownerrez.com/support/articles/channel-management-api-integrations-airbnb-common-issues-questions#changes

If I want to create a custom link in airbnb, but I am linked via API, would you recommend I disable the API, while I make the changes? 

Well, you don't have to disable the entire API, just disconnect that 1 property for the 5 minutes it takes to make the change, then connect it back up again.