How to take a few things out of staging? (And a question about undocking)

[Yume]

Basically I created a small space craft with a docking port attached and saved it in the sub-assembly loader. Now I have a craft that is supposed to take 4 of them up to orbit via a HubMax Multi-Point connector (obviously with 4 docking ports on it). But my problem is that all 4 of the crafts have their thrusters and such in the 0 stage and I don't want them there. I also have a problem with assuming control of the decoupled craft: I tried using "control from here" on the docking port and on the actual MkI Lander Can (with a kerbal inside) but it doesent give me control of the craft. It still leaves me with the main ship (which is controlled by a stayputnik, the main ship is unmanned). I'm sorry if I typed a lot, I just wanted to give as much info as possible.

[GrihanOs]

You can move engines between stages by clicking on them and the dragging them to the stage you want. You can also create new stages with the little "+" button between the stage boxes, and delete empty stages with the "-" button, and rearrange existing stages.

For the second question, you can cycle close vessels with the "[" and "]" keys.

[Yume]

Thank you so much that worked like a charm! It was really getting on my nerves having to go to the tracking station just to switch a craft.