If I select a position on the map, for example using search or just by touching the map and then try to set it up as a favourite I subsequently find that it comes up on the map in a position slightly, but significantly, different from the originally chosen position.

1. Any ideas why this discrepancy occurs?
2. What is the best way to set a favourite more accurately?
3. Is there any way to adjust the position of a favourite without removing it and re-saving it?