Sounds like you have a machine with set length and width for each stitch. At some point you will want to graduate up to a machine that has variable stitch length and variable stitch width, plus independently adjustable needle positions.
In terms of working on the quilt you have posted, now is not the time to be changing your needle position and seam width. Until you finish this quilt, I would keep everything as you have been doing it. Just adjust the sashing strip lengths (shorten them to match your blocks) and you are good to go.