yeah no worries. Once its a component all you have to do is double click to get into it and then you can edit it without messing with anything outside the component.
It helps to group things in components anyways as it helps keep sections and part organized. For example if you have a setup with tank, lighting, rock work, and plumbing. You can have each as a component and then make the one big component. That way you can move the lighting, as a example, out of the complete design and work on it without having to select the individual parts of the lighting setup, moving them out, and then accidently selecting something outside the component and messing it up.
Just makes it a lot easier with big projects.