I noticed if I activate the plugin on a new or pre-existing site, the token and server URL field are automatically filled in with the most recent one saved on any other site.
This is using the plugin on a network install as a simple site plugin not as a multisite network plugin.
As I have dug deeper, it seems the settings are stored only once in the DB under wp-piwik_global-settings in wp_sitemeta table. Each new site overwrites this and there doesn't seem to be per blog/site storage. Presume normally it is stored in wp_XX_options in a multisite?
Seems odd that no one could store details to allow any other piwik install and need to use a single auth token for the whole network?
Is this by design or is it a problem in the plugin or my install?