I don't know what's going with my Gimp, but for some reason when I tried to crop a single layer it cropped the entire canvas. I know that this is abnormal because I've been using Gimp for about a couple weeks for fashion/outfit design (instead of Polyvore) and I have had no problem with cropping before.
All I do is just drag the rectangle over my image, press enter, and I'm done. I can position my image next to any pair of shoes I want... Did I accidentally press something on my keyboard to change the settings?