Go into Layout Mode, click on any of the fields, and edit. You may have to make the portal wider or the existing fields smaller.
Easiest is to click on a portal field, duplicate it, change the reference field.
Thank you Steve! Copy, paste and expanding the portal to make room for the new field worked! I tried this before but i didn't know it had to be in alignment with the other fields. Thank you.
Alignment is not mandatory but the new field must be completely inside the portal