Well, now you know the answer! I shall, however, add a little more information.
If you look at the winding of the thread on
any spool / cone / reel, you'll see that it is wound in either of two ways:
- Like a bobbin, just going round and round from top to bottom to top
- In a criss-cross pattern
For the first type, the thread is designed to unwind from the side, with the spool rotating. Don't use these with a cone holder as it will cause the thread to twist and become knotted. On your sewing machine, use the upright spindle.
For the criss-cross wound spools, the thread needs to be dispensed from the top, preferably with the cone being stationary. On a sewing machine, use the horizontal spindle.
HTH