This is a quote from another forum: “Custom settings are often referred to as "custom film recipes", as these do not store all your camera settings, but just the ones available inside "IMAGE QUALITY SETTING ’", and they mostly (if not exclusively) affect the JPEG alone (like FILM SIMULATION, GRAIN EFFECT, WHITE BALANCE, HIGHLIGHT TONE, SHADOW TONE, COLOR... etc).
My question is if settings other than those about Image quality, such as function button assignments, etc., when once set via the various menus will apply to all custom settings C1 - C7. Camera is X-T3, if that matters. Thanks for enlightenment.