I apologize for the long-winded background.
I am having an unexpected issue with my 20 mo old German shepherd male. Since the day I brought him home I have taken him everywhere with me that I am able. I use it as an excuse to teach him how to behave in a variety of situations .
He instinctively knows not to mark in the house, except for last Christmas he marked th tree. It seemed that having a tree indoors confused him. It was an easy fix. I kept a very close eye on him and stopped him when he lifted his leg.
I also have taken him to home depot and petsmart. (Petsmart because he isn't dog friendly so I start off far away from another dog giving commands and move closer to gain dependable engagement) Anyway, he hadn't marked anywhere besides outside until recently. I took him to a vapor shop. They had a potted tree that he marked, so the next time we went in I kept him away from the tree. He lifted his leg on the stool instead. I was aware that he desires to mark in this place so, like with the Christmas tree, I kept a very close eye on him and patted his butt and said stop. He listens very well, and did stop. I can keep going as I have but I am hoping someone has a bag of tricks that makes the indoor vs outdoor marking more black and white to him?

"I patted his butt and said stop".

Hopefully there was a bit of firmness in your pat on the butt and "stop".

If not he could very well take that pat on the butt as praise.

Since your there to witness it this would be a time for consequences for his actions.

If he is the submissive type the you only have to raise your response to the point of him understanding it's a correction.

His stopping when you gave him the pat on the butt could just be that you broke his concentration and not necessarily a negative reaction to his peeing at the wrong time and place.

Thanks, you are probably right. He knows what stop means but to him it is just stop what you are doing for right now, because that's how I usually use it. I will see if being stern will make him understand that he is breaking a rule.

His temperament will have a lot to do with the level of correction.

When it's over, it's over.

Any corrections need to be firm yet fair with a calm demeanor on your part.

Showing him how upset you are is non productive simply because they wont connect it to what they did a couple of mins ago.