Dual Monitors - Change the direction of the "edge"

Hi guys,

Hard to explain this properly. Basically have 2 monitors - one of the left, one on the right.

One on the left is my primary monitor, but when I want to go the monitor on the right hand side, I have to move my mouse the whole way across the left hand side of my primary monitor onto it (where it then arrives on the far right hand side of the second monitor)

I need to change this so that when I move from left to right, it acts like there is no barrier between the two monitors and just goes between them easily.

Hope that makes sense - any ideas? I've swapped the leads at the back and then changed the primary monitor but that makes no difference