How to use "adjust price" port

[Pedros]

Have just been tying to use this. Expanding o the port givs me a messae "an only be used duing a trade action"l if I ordr a "sell" for the unit the action happens immediaeely, so I don't get the adjuskment!

[Pedros]

OK, answer discovered. Ordeer the trad as usual and the option to adjus is offered auomatically (providd you can afford it!)

[XyreX]

This does not work for me. I Have access but never get asked to use it. Also that behavior seems bad i. General. I wanted to make a trade the requiered the action to be affordable but that was impossible. Did another trade instead but did not get asked to use the port

[Jeromie]

While its not the most intuitive, I never had any issue with it. If I look at your last game from your perspective, I can buy and use the port in all legal ways I can think of.
I even get suggested to use it when trying to buy for more than the money available:
"Buy 2 Cheese for 12 each? 20-24 = -4 You don't have enough money, try using a port"

Then I can use the checkbox to use it.