To do this, the user must grant cookie access to the viewer's browser page. Otherwise there's no way of knowing when a specific user comes back in a new session.

The idea is that the browser viewer app's container page would reference the cookie to an already-saved preferences file (much like an installed viewer writes the prefs to the system for later retrieval). As long as the cookie was valid, those prefs could be loaded even prior to logging in, and thus shared between accounts using that browser.

Note that this would not transfer prefs between one browser and another (computer to tablet) loaded by the same person, each device would need its own cookie. Sharing a cookie from another device is a bad idea for security reasons - it can be done, but is not recommended.

Browsing in pages that disallow cookies (incognito mode) would of course defeat this method.

we are working on this.