For Quick Find Views, the changes apply to everyone using the Search for records box for the entity. For Advanced Find Views, the changes set the default for everyone using Advanced Find for the entity. Users can change the columns for individual Advanced Find searches.
When the entities are published, a confirmation message appears.
If a system entity has been customized, it might have different properties than what is described in Help. There also will not be Help that is specific to the custom entities your organization creates, though there is Help that describes how to create and use custom entities.