The auto-connection that happens if you put a part near other part with your mouse is sometimes helpful, but most of the times its not. For example if you have a small part surrounded with big parts that have much bigger connections, then you will never be able to connect to that small part. I think that there should be an option in settings that allows you to turn off that feature so you can connect your parts with the part you are aiming your mouse at.
@donwea yes