Toggle fiducial marker at move slices

I was helping a collegue with 3D slicer today, where we were using a 3D echocardiographic volume and fiducial markers.
He installed it today, and was not able to toggle a fiducial marker and then let all slices merge around this point.
On my 3D slicer it is possible, and i feel like i did something to make it happen when i installed it.
However, i do not remember where it was. Anyone that can assist me so my colleague can get this feature?