[Solved] Big knobs, how to screw them on?

I feel really dumb at the moment

but I can't figure an easy way to screw on the two big knobs for volume pot and data encoder. There is a conical brass piece separate from the knob, and then inside the knob is a nut, but I couldn't get the screw to get inside the nut.

How does that work? And is there an easy way to take them off afterwards?

Cheers!

you can take of the cap, nvm, after reading again, it looks you did find that already xD

No I didn't know that!! thanks that makes a lot more sense now