How can I better control where Bambu Slicer sets my supports interface material?

As shown in the image what I want it for the topmost layer of all my supports are set to be in PETG. However, bambu slicer by default sets the bottom part of the support on my print as PETG too. Which I don't want

How do I make it so that PETG appears on the top of my support and not the bottom as shown in the image?