How to propagate changes site wide?

Hi. I'm new to Multisite and have a question - how to we propagate/standardize changes that we make on the main site to other sites? Some examples would be:

1. If we added/deleted a widget on the sidebar.
2. If we change settings of a plugin.
2. If we created a new menu bar on the homepage (e.g. contact us) and want.

Thanks!