Possibilities to add Custom fields in Defect Tracking Module

Thank you vinniew for sharing your thoughts ! 

I am particularly looking to add more custom columns and enhance the default severity values to custom values to meet our company standards. It appears like Zephyr Enterprise internal defect tracking system don't offer to customize defaulted values except for Priority. Again priority and defect status values are restricted to change the existing values but not feasible to add more values if needed.