Custom Fields with many categories

Currently, the custom fields assignment with many categories and different (fields) is very confusing and complicated to set up.

It would be ideal if the fields could either be grouped or inherited.
Or you could define forms where you can assign the fields and then you only need to assign the forms to the categories.

Or at least make it easier to click on the categories. Checkboxes instead of dropdowns.

thank you for rethinking this solution.
Corinne