mkc

True on a longarm that we always adjust bobbin tension first, but OP is asking about quilting on a domestic machine, in which case most recommend adjusting top tension first and only touching bobbin tension if absolutely necessary.

Also as a note, many domestic sewing machine manufacturers offer a "low tension" bobbin case as an accessory that works well for embroidery and FMQ.

CanoePam

I have adjusted my bobbin tension for special purposes on a domestic machine too. You just have to be careful to mark the original screw position and to take it easy. But if you are trying to quilt with a heavy thread in the bobbin, it sometimes has to be done.

Onebyone

All new machines are set at factory for poly thread, most common is the 40 wt. using an Organ needle. The needle may have their brand name but it is an Organ made needle. Japanese steel. Every machine tech I have talked to at quilt shows have told me that.

QuiltE

Also ... A good machine tech can re-set your machine to the thread (type and weight) you most commonly used. Each will have their standard thread they service and then set it with, so unless you tell them you want it otherwise, that will be what it will be.

Of course, you need to remember that if you then re-set the tension for a different thread, then you now do not have your machine set for your most common!