Use Home | Select > Physical Connection to select all the segments and then use View | Object Inspector to adjust the track width of all segments connecting two points. To change a net globally first set the Tracks filter, use Select > Connected Copper and then just as before adjust the width using the object inspector.
that works but on my last instance of doing this the two tracks that i need to move in order stop a collision cannot be moved, i will have to remove them and start again. Just another one of the usual BUGS that Farnell and Altium will pretend don't exist......
