Are these fields or records?
Records will display vertically in a portal and that's the only way they will display in a given portal.
Separate fields of the same record can be arranged any way you need. After exiting Portal Setup, you can resize the portal row to make it taller and then you can rearrange and resize the fields as needed as long as you keep them within the portal row.
But I am wondering if the fields that are "coming in horizontally" might be better off as separate portal records.