along the top of the screen, right under the row of icons will be preferences for the current tool.
If you look there you will see a text box for tolerance. That is the amount of luminance change from the original pick that will be selected.
Another tool that may work better for you is the magnetic lasso tool. This works similar to the lasso tool, but it snaps to any high contrast edge it gets close to.
Like I stated before, it is not the best way to make cutouts though. The best way is to use layer masks, which are available in elements, although you have to do a bit of tweaking to be able to use them in elements. (they are in there, but hidden, and you will need to download an action to be able to use them)
If you look there you will see a text box for tolerance. That is the amount of luminance change from the original pick that will be selected.
Another tool that may work better for you is the magnetic lasso tool. This works similar to the lasso tool, but it snaps to any high contrast edge it gets close to.
Like I stated before, it is not the best way to make cutouts though. The best way is to use layer masks, which are available in elements, although you have to do a bit of tweaking to be able to use them in elements. (they are in there, but hidden, and you will need to download an action to be able to use them)