The problem here is that the ability you are calling, Ref-save, has a roll template inside of it. This roll template is what is performing the roll. If you want to modify this value, you will need to modify it inside of the ability itself. If it is a user created ability you can simply change it in the Attributes and Abilities tab. If it is an attribute specific to the character sheet. You will need to create a new ability based off of the original and make the necessary changes. Quick tip on the second option. Click the regular ability to show the roll in the chat, and then click the up arrow in chat to see the specific roll template that was used.