Bobbins in one place? Spools in another?
How frustrating it is when you think you grabbed black thread when in reality it was navy. Been there, done that.
Some assembly required. Set Bobbin Logic on a flat sturdy surface. Insert an end of the post into the hole and gently push till you feel it bottom out.
You can very gently tap it with a small hammer till it goes in. Should your post fall out you can use a tiny tiny bit of super glue to hold it in place.
Make sure you follow the directions on the packaging of your super glue.