I've made two custom transaction line fields and applied them to Journals, but when I edit the Journal forms I can't find the fields to make them visible or decide where to put them. How are custom line level fields done on Journals?

Check the form(s) you applied to: Screen Fields > Lines

I'm only finding Custom Transaction Body Fields there, no Custom Transaction Line fields.

Figured it out. Just scroll to the right. There is another Lines sublist that's off the screen.

That was it!