I'm trying to copy/paste many distributions from JMP into a PowerPoint. Sometimes the distributions are pasted as column and sometimes a row. I would like to "paste" them into a row, but can't figure out how to specify.

I have not seen this behavior. If I have the JMP report structured the right way, select the items I want, copy and then paste-special into PowerPoint everything goes fine.
The only anomaly that I have found is that if I have a JMP report with the distributions selected, then rearrange the report (perhaps by arranging in rows), then choose copy (because the distributions are still selected), it may not capture the rearrangement. I need to deselect the selection and re-select the rearranged distributions before copying.
If this does not answer your question, you will need to provide more details on exactly what you are doing.