I use steam a seam fuse and really like it. Did you fuse the appique to the background fabric, were you using quality fabric? I also don't use a huge needle, a 70 or 80 is about as large as I go, unless I am using a 40 wt. thread, but that is mostly used with a blanket stitch. When I do satin stitch, I only allow the needle on the zag of the stitch to fall off the applique, the rest of the stitch is on the applique fabric. Also consider the size of the applique, if it is large, then use a wider zigzag, I usually use between 2.5 - 3 on my Bernina. I love doing satin stitch applique. Hope this helps your problems.