At the moment when I choose Full Screen Preview it shows on my second monitor, how can I make so it shows on my main monitor where the editor is.
You don't. Full screen preview is second monitor only. *shrug*
Wish I had a different answer for you.
@Triem23 That's a shame. In the meantime I have maximised the preview window and saved that as a Workspace View.
Probably the best workaround.
You can also float the Viewer panel and squeeze out a little more space.