Everything has a user. In this case the user is the person using word, be it me or someone else.

The bullet point list on the toolbar.

As long as you are simply applying bullets to Normal, and maintaining Normal as your style; and as long as you wish to maintain 18 pts after in your Normal style, I don't know of a solution. It is easy enough to create a new bullet style with 0 pts after, but this you would have to apply as a separate style. Have you considered creating such as style and making a shortcut button on the Quick Access Toolbar?

Thanks for your help.