7.6 - Create Opportunity and RLI simultaneously - change available RLI fields...?

We have recently upgraded to v7.6 of Sugar, and one of the great new features is the ability to create an Opportunity and its associated RLIs simultaneously.

However, I cannot see how you can change what fields are available when you create the RLI underneath the opportunity. For example, we do not use the "Best" and "Worst" value fields - we simply use "Likely". 

Presumably there is somewhere I can change these fields in Studio...? If so, please can someone tell me where! It is in none of the obvious places...