Does your number 13 look like this one on the screen? For appliques, I generally use a stitch similar to #6 and decrease the width. It gives a secure stitch to the applique piece. There may be a plain blanket stitch on your machine too. It's shown here as #14.
Geri B, The stitch shown here as # Q-16 I use to secure binding on quilts. I call it the double flag since it stitches two across then goes down to the next "flag" stitch. The length and width can also be adjusted depending on where I want the lines of stitches to be. Hope that helps.
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