how do I get the memo field to carry over the memo from the SO to the IF?

You can do it with workflow.

You recommend that over script?

Its my preference since I'm not a developer, haha.

Workflows are much easier to quickly understand what is going on, and for really simple tasks like this, that is helpful.

@Sandii has a point. If you enable logging, you can see on the record what failed.

Yeah workflow is likely easiest here- Type: Transaction Sub Type: Item Fulfillment On Entry-Set Field Value - Memo Set Value to Created From: Memo