To adjust the dialog size to better fit your screen, you can use the tool in the center of the dialog that looks something like this (it may vary slightly from dialog-to-dialog that uses this tool):
If the dialog is way too large, we suggest you click the User Small Dialog button. It sets the boundaries of the dialog to a size that will work with most monitors. If you need to adjust it a bit more to be either a bit smaller or larger, then click the left and right icons to move the dialog size either smaller or larger. The program may exit the dialog and request that you come back in after it exits. This is so that it can adjust the size correctly for you. When you bring it up again, it should be sized correctly.
You can also click on the number in the box above and type in a percentage value.
If the dialog does not appear centered after you make your adjustments, just grab the title bar with your mouse and reposition it. The next time you enter this dialog, however, CMD will automatically center it based on your dialog size selections.