UV Island selection in edit mode?

Good Morning All,
If I select all in edit mode window, select the individual island in the UV window, how do I then de-select all the other islands in edit window.
So just the selected island from the UV window is displayed in the edit window?
Cheers
A

obraz
There are two modes in UV editor.

In one You have visible things that are selected in 3d and separate selection in uv editor.

obraz

And second mode where every uv is visible, but selections are in sync.

It is the synced version I need to use, but I would like to be able to select all the ngons within the island that is created by the seams.
I can only see how to to sync individual ngons?

Type L over the polys that compose the Island in the 3d viewport.

Thank you, that’s exactly what I was looking for

You are welcome.
Shift G is also a good contextual selection shortcut.
It gives different selection’s choices, regarding if u are in vertex/edge/face.