Well i tried to move the new one into the broker slot while holding shift but all it did was to put the new crate in the old one. Tried with control too. How can i upgrade a crate without removing all the items ?
Also, at least in inventory slots you have to _not_ press shift or control. So open the one you want to replace and just click and drag the new one.
you have to empty your old broker crate then go to a broker NPC and remove the old crate from the broker slot that it's in , then you can put the new crate in that slot and put your items in it , you will also need to go to your room and place the crate in there if you want to give people the option to go to your room and buy stuff from the box to avoid the broker's fee