In Elements Crop tool snaps to edges of the photo automatically. You can try doing one thing to precisely make crop boundaries
1.. Go to Edit>Preferences>General and select the option "Zoom with scroll wheel.
2. First zoom in to the image using scroll wheel and then use the crop tool to precisely make the boundary. You can also use the shortcut "Ctrl + +" to zoom in and shortcut "Ctrl + -" to zoom out and precisely make the crop boundary. But using scroll wheel to zoom in and out will help you better.
While using crop tool you may not be able to zoom, but after leaving the mouse click ,zoom into the image to make exact crop boundary by dragging.
We can control the zoom digitally by entering digits into the % box near the bottom left of the workspace. The CTRL-PLUS-KEY (or minus) takes big jumps, but we can change the % by simply entering another value into that box and hitting the Enter key. So we can control the zoom/shrink with pretty much all the precision that may be useful. Controlling the zoom is not usefull in getting precise control over the crop tool, at least partly because it wants to snap. I still want to control the crop digitally, by increments I select.
There is probably a technique for turning off the snap.. If I EVER knew how to do it, I have forgotten. That would be at least one way to get some control over the crop/select tools. Please tell me the navigation for turning off the snap. Please. I have very often placed my left hand over my mouse (right) hand in a vain attempt to make very small movements, to more precisely control the crop/select.
Is there no way to move the crop lines with digital precision? Is there a plug-in available from a third party?
What version of photoshop elements and operating system are you using?
With the Crop Tool you can press and hold the Ctrl (cmd) key to turn off the snapping while moving the crop boundaries.
For selections you might try Select>Transform Selection and then you can enter precise numbers in the tool options bar.