Function Buttons and Presets

Perhaps I misunderstand how the function buttons can be used. You have the choice to toggle or go to presets. It doesn't appear you can choose a custom preset. This is...a huge bummer. As someone who shoots a ton of nature and wildlife I want to access 4k60fps frequently. I'm generally shooting 6k open gate 24fps. I don't understand why we aren't given the option to just toggle back and forth when you CAN do that through menu options.