So agree with jimbo non-intuitive to use but I will persevere.Will plan a route with start and finish waypoints and shaping in between and go off route and then recalculate and see what it does. Then do a route with several waypoints only, and recalculate. No definitive answer so a lot more experiments needed
There is one shortcut which, once you know it, makes plotting routes much easier. When you want to drag n' drop to modify a route, try this:
1. activate the 'hand' icon so you can drag the map around on screen
2. zoom in until you can clearly see where you are dragging to. Use the mouse scroll wheel or keyboard +/-
3. place the 'hand' icon over the active magenta route line,
hold down the 'ALT' key and
hold down the left mouse key. A black line appears - keep holding down the keys as you drag this black line to the road you want to use. Then release the L mouse key.
OK, you need to use both hands to do this, but it takes only moments to drag and drop a route.
To make changes to the points in the route, open the route either by double clicking its name (though this also zooms out the map to show the entire route on screen) or R-click, Open (which leaves the zoom level unchanged). Now you see a list of the waypoints and shaping points. If you click on a shaping point a brown circle on the map shows the location of that point. If it is in the wrong place, delete it, let the route recalculate, then drag it to the correct point using the method above. It really is easy once you understand the basics.
One final tip: once you have created the route, open it as described and look at the waypoints and shaping points. Some of the shaping points will be announced (I think this happens if there is a named feature at that location). I turn off all announced points (R-click, select from menu) except for the start and end waypoints, and the shaping point closest to the start (then I can select to 'go' to this point when I start the route on the Nav V).