How do I get my sewing machine needle to stay in the center

SOURCE: Kenmore sewing machine 385.1960180, problem with needle centering

That sounds like it's definitely an internal adjustment. The machine will need to be opened up and the left/right adjustment taken care of. Is this machine one that you can open the top easily, or is it the type that has the front and rear shell?

SOURCE: bobbin holder won't stay put

If the bobbin case/holder is trying to lift up and the thread is staying partly around it, your bobbin case may have turned part way.
Remove the needle plate and the bobbin case. The outer edges of the bobbin case should be very smooth. I suspect you may see a needle hole in the flat area that was under the foot. If so, you will probably wish to take it to your dealer and show them. They may smooth it or recommend replacing it. When the bobbin case is placed back into the hook cup that it sets in, the retainer at the 11 o'clock position on it should only allow the case to lift up about 0.8 to 1mm at the most. If it will lift up more than this, press down firmly on the retainer and move it closer to the bobbin case. You must have enough room for the thread to pass between the retainer and the bobbin case, but too much clearance will allow the bobbin case to turn in the machine and it will be damaged by the needle.

SOURCE: needle wont pick up bobbin thread

timing issue, need to have serviced.

SOURCE: sewing needle for model 4562 sewing machine

http://www.singerco.com/resources/operation_basics.html

this will give the info you need.

SOURCE: twin needle treading for singer sewing machine 3116

Yes, put your second thread in a cup behind your machine and thread your machine like normal