You can get back to the pension income by entering 1099-R in the Find window on the upper right, click Enter, then the Jump To. Go through until you come to a small summary and choose the 1099-R to edit.
Same process, except enter social security in the Find window.
If you mixed them up and put one or both in the wrong place, when you get to the little summaries, you can also delete any entry that doesn't belong there and enter it correctly by going to the other topic.