"The border shape created with QuickStitch™ when I click inside the area is not the one I want."
The pictures used should have well differentiated color areas, which may be solid or stippled, to fill easily. Clipart is excellent for this purpose. If there is a gap where the same color flows into another area, the fill will not work. If Color Tolerance is switched off then switch it on in Preferences. Color Tolerance will then allow you to preview the border, which should reveal any problems with color areas in the picture. You can then alter the picture in the Picture window. Alternatively, use the Freehand or Point Create functions to place the satin border.
"A QuickStitch™ line has a double layer of stitching in one section."
If border areas run into each other, two layers of stitching will be produced by the QuickStitch™ border functions. To avoid this, split the colors on the picture in the Picture window. For example, put a visual 'end point' for each border area. Alternatively, use the Satin Line Trace function.