How do I back stitch - Brother SE-270D Computerized Sewing Machine

It is quite likely that the machine needs oiling. Somewhere in the drive train parts that need to move freely are sticking and causing the stitch length lever to drag back to a shorter stitch. Use a good quality sewing maching oil on everything that moves. Preferably use singer oil. under no circumstances use a "General Purppose oil". Machine oil is designed to evaporate leaving no residue behind whereas general oils simply dry out leaving a horrible brown varnish that actually gums up the machine. If your machine has brown varnish everywhere you look then this is probably the problem. You will need to thoroughly clean the machine with paraffin oil (kerosene) and then thoroughly oil everything as above.

Stitch width set to zero, turn off any decorative stitch selections, stitch length to ~2 or 2.5.

I would divide the 185, by 14 and then increase one stitch after that many stitches, the increase will be even and it may look like it is part of the pattren.

K1 Yarn forward K1, K1Yarn forward K1 all into the next one stitch. This will make 5 stitches out of one on the right pin. I would then slip, one at a time is easier, those five back onto your left pin and knit them back onto the right pin. Knit these five stitches on the right pin (that you have just created out of 1 stitch) all together which will bring you back to the original stitch. Lots of different ways to make this stitch. Don't forget that by putting your Yarn fwd (nearest to your body) then knitting a stitch it will make one of your five. Some patterns say yon or Yarn over needle. Exactly the same stitch. Hope I haven't made this too confusing. It's a fiddly stitch but just practice.

This video will probably help:

Crochet Front Post Treble Crochet FPtrc

To make the stitch on the back of the stitch, you would insert the hook from the back side of the project and work the treble stitch on the back.

How to Crochet Back Post Triple Treble Crochet Stitch

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The "dial" in the back is for decorative stitches which require a "programmer" to be inserted with the stitch formation you want to form. For a straight stitch no cam is required in the back of the machine. The three dials on the front:

Upper Left: Stitch selector
Upper Right: Stitch lenght
Lower: Stitch width

Using the upper left dial select the straight stitch picture
Using the upper right, choose your stitch lenght
Using the lower, choose your needle position, left/center/right

then you need to call the shop that serviced the machine & tell them
about the problem that the machine won't backstitch & see what they
say

Take a look at the stitch length dial. If you turn that dial counter clockwise (to about 7 o'clock), it will set to stretch stitch. Then all of the stretch stitch features will work. When you want to go back to straight stitching, just move that dial back to what ever stitch length you wish.

You don't use the back stitch or reverse button during embroidery since you are stitching out a design and not using your utility stitches. If you missed some stitches and you want to re-stitch a portion of your design or what I think you mean by "back stitch", there is a button that either says reverse, back or shows stitches with a + and - so you can backup and go over the area you missed. It usually lets you back up a stitch at a time, 10 at a time and 100 at a time. I use it sometimes to get a thicker satin stitch if it looked too thin the first time. Just be careful not to go over it more than once as it might bunch up. They also show a button usually with a spool on it so you can back up an entire thread color. It will probably be in your manual under "what to do when the thread breaks" or something similar. Happy embroidering!

It does not matter what pattern you select, if you have the stitch width dial on 0 or set on straight stitch then that is all it will do, to do patterns you need a close stitch length about 2 or if it is not numbered get the stitches close to suit yourself and the stitch width on the widest number.