This machine also has an "immediate tie off" button that I can push each time, but I wanted to use the programmed one that will do it each time until I turn it off.

I'm not sure what you mean. If it's programmed to tie off at the beginning of each seam, how does the backstitch button activate it?
The manual doesn't mention that.

Good luck! My machine is with the doctor right now, so I can't play with it to see what it does...

The machine probably assumes that there will be some sewing done between tie off stitches. First you tie off, then you sew, then you tie off again. If you don't sew after you tie off, the machine won't "understand" why you want to tie off again right away. The only way to do that is to reset the stitch and start over.

I recently learned in my machine quilting class that I need to pull the bobbin thread to the top before I tie off. The way I can tie off is by setting the stitch length to .4 or .6 mm and taking 5-7 tiny stitches. Then I will sew my pattern in regular stitch length. I finish off with the reduced stitch at the end and trim the threads. It makes a nice clean seam for quilting inside a square or pattern.

My machine has the tie off stitch selector. When I engage it, the back stitch sets the stitch at the end of the stitching. I just love all of my options.

I do the tie off on both ends and it works for me....

On my Viking I can go into the main menu and turn on or off auto fix. When on it fixes at the beginning of each seam. When off I have to manually select the fix button.

Your might try the Pfaff.com website. I have a 7570 and I have to select that function whenever I want it to happen. I'm not sure why the machine would know if I need to tie off otherwise. I am constantly starting and stopping when I work at the machine (not always at the end of a seam) and raising/lowering the presser foot.

I've only used the tie off stitch when sewing garments. I don't use that particular function when I piece because I always am sewing over another seam. Where would you use it when you quilt?

By the way, sewing on a button using your machine is the only way to go. If you have to handsew one it might end up in the terminal "round-to-it" repair pile.

So far I've only been sewing on a scrap trying to get the **** tie off stitch to work. I thought I could use it sewing the seams on my quilts since I usually do a tack every 12" or so anyway, just in case a thread comes loose it wouldn't be able to unravel the whole seam. A leftover of hand quilting. Every time I stop to readjust the quilt, I wanted it to do a tie off when I start again.
I've pretty much given up on it though. I guess I'll just have to use the "immediate tie off" button that I push each time, but it's a shame this machine has a "programmed tie off" (that I don't have to push each time) and the manual doesn't explain well enough to make it work.