I had the same problem. The margins in scrivener were much wider than the margins in my word doc. I changed the margins in scrivener to be the same approximate width as in word and it then exported to word properly.
Are you setting the right indent to be extra wide? It’s a common mistake to think Scrivener has margins the same way a normal word processor does. Because you can (if you don’t use page view) adjust the editor’s width any time you like, Scrivener doesn’t adhere to a line length normally, but instead shuffles the words around to fit the width of the editor. But if you try to set left and right margins in Scrivener, you’re essentially telling it to pass that setting to whatever format(s) support the right indent, and that will cause your words to scroll off the edge of the page.
In scrivener, select a paragraph in one document where this problem exists on the output. Expand Scrivener’s editor as wide as you can, until you see the right indent marker (looks the same as the left indent marker). Drag that marker off the ruler, then compile and see if it fixes the problem.