The "Project / Function Data Panel" Dynamic GUI can be accessed via Settings → Project / Function Data Panel
The Dynamic GUI settings panel works in much the same way as for Rooms, Items & Occurrences.
One important exception is that a Flag can be made visible in the Properties Panel when the Function is selected in the Rooms module.
This is controlled by the "Function Location" dropdown control that is displayed at the Flag level.
All of the Function Level names are displayed in the dropdown (including "Functions - (All)" which applies to all Function Levels)
If one of the Function Level options is selected then the Flag and associated Fields are displayed in the Rooms Module Properties Panel for that particular level of the Function Structure: