I'm playing PC version, and there's no way to change it. The stats should appear in a partially transparent window, but I agree it does make it a little hard to see the green/red changes in your stats the item would produce. You can move the item around in your inventory slots (like Raze recommended) or move the moust slightly over the item if the green/red stat changes are too badly obscured.
However, it never really bothered me - it shows the new item vs. the currently equiped item in the pop-up, so I found myself mostly comparing stats of the items (rather than looking at the difference in my character stats).
