I'm posting this for a friend.

They have an 18 month old entire male who's recently started weeing on people, children too I believe.

They've recently moved house, and changed the car.

My intial thoughts are that the changes have stressed him out, and the my advice would go back to basics with him, but I've no idea really regards behaviour.

What would your thoughts be on this?

:)

It is arrogant male marking and should be stopped immediately; seen this from male dogs who have no respect for their owners or anyone else............

He is also making his mark on his new territory.

Thats what I thought too, but how would one stop the dog from doing it?

Be on the alert and as soon as he starts, say a firm NO while removing him from the room so he is left on his own for a short period.  Hopefully, he'll soon get the idea that if he wants to be with his 'family', he needs to behave.

it's short sharp shock time - of the verbal variety i hasten to add!

only while nips has never weed on a human we've had a couple of episodes of "marking" in other people's houses recently. it's mortifying and i'm not prepared to tolerate it so he's currently watched like a hawk (the first 10 minutes are danger time) and as soon as i see even a twitch of the "cocking" leg, i bellow "no!" at him. he's not exactly a delicate little flower but to be honest i don't care if it does make him jump because it also stops him dead in his marking tracks!