I press those seams open. The default on my machine is for a 2.5 stitch and I drop the stitch down to 2.0 when pressing seams open. If you set the seam, as you normally would before pressing, it makes the seams open easier. And I have found, for me at least, when opening seams, if I put the darker side of the fabric to the top it is easier to find the lip of fabric and open. That sounds more confusing that it is in reality:-)