I've never come across 'auto-scrolling' as such.
As long as a GPS is in 'GPS mode' - it will show you where you are, and in a map view that means centred on the visible map (ignoring subtleties of Track up/North up for the moment). As you move, the map continually re-centres to cope with that, its what a GPS does.
What I think can happen, is, as soon as the map is manually scrolled for any reason (eg just touching the front pip can do this) - or you do a Find, say - the display drops into a different static 'pointer' map mode which is superficially just the same as the GPS map mode. It can be somewhat confusing, but one clue is a white pointer on screen, very similar to the typical mouse pointer on a PC.
[edit] So in the scenario you describe, as soon as you once try to compensate, you have dropped into the static mode and will stay there - getting the effect you describe - until you get out of it by using the Quit/Page key or by restarting the GPS. [/edit]
The way back to the scrolling map mode is simply pressing the Quit/Page key, which is the top right one.
Often a single press is sufficient to clear the 'pointer' mode, or you may have got into a deeper mode where you have to press Quit repeatedly to cycle through several pages to get back to the GPS map page that way.
(Top Tip: go into setup and remove all the pages you rarely use, from the page cycle. Including the Menu page. Ultimately the Quit/Page key just becomes a simple switch between your 2 favourite modes - I find this makes the GPS much slicker to use.)
