Trade Carts and Cogs...please do what I want!

I’m sure I must be missing something, but I know the best trade route is the longest/safest one. If you have multiple markets or docks, it gets very frustrating when they return to your closest market or dock rather than the one you sent from. This is quite irritating with cogs, since docks are usually very busy on water maps. I have seen one YouTuber say you have to delete all other markets, but I can’t function with only one dock just to allow an ideal trade route. Is there a right-click or some way to get carts/cogs to move between specific markets/docks? I feel like surely the developers addressed this and I’m just asking newb questions.