Ditto to all that was said before. But the pressing is very important when making something that has so many intersecting seams in the middle. Press them going all the same way around in a circle. Then the seam allowance is distributing the bulk around and it makes it lay right. (This has to be done while you are making the block pieces to make the block.) So, when it is put together it swirls in one direction.
Pressing is a big part of quilting. I use a dry iron and pressing is an up and down motion. Don't scrub! bias will grow and distort very easily.