Local parameter override
Locally modify a shared parameter
Sharing entire layers or a simple Modifier group will cause the purple Share icon to appear on a large number of lines in the Stack and Properties panel.
This lets you synchronize hundreds of parameters in just a few seconds, but you may want to locally regain control over only one of these parameters.
To do this, simply click on the connection button again to bring up the Quad Menu and select Unshare.