How to set Extruder Change start/end positions

[merlincode 0]

I'm a newbie  running Cura 4.6.1

I want to change Cura so that it returns to the Prime Tower before changing over the temperatures from one extruder to the other.

The current default setting is it stays where it is in the print, changes temperature, and then moves to the prime tower.

 I know the settings to do this need to be set up in the printer profile extruder settings and the settings in question are:

 

{machine_extruder_start_pos_x}	Extruder Start Position X	The x-coordinate of the starting position when turning the extruder on.
{machine_extruder_start_pos_y}	Extruder Start Position Y	The y-coordinate of the starting position when turning the extruder on.
and
{machine_extruder_end_pos_x}	Extruder End Position X	The x-coordinate of the ending position when turning the extruder off.
{machine_extruder_end_pos_y}	Extruder End Position Y	The y-coordinate of the ending position when turning the extruder off.

 

but i'm not sure what the syntax is to set these.

Please can someone help?

Thanks

Maurice