One problem some knitters find with double pointed needles is that they get a "ladder" or column of stretch stitches between the needles. Fans of using the magic loop method of working in the round with a long circular can find the same thing where they divide their stitches.
The ladder is caused by there being a different amount of strain on the first and last stitches on each DPN causing stitches to distort and the gap between them stretch.
Thankfully there is a simple solution. Every few rows, move the gap between the needles. For example, work two more stitches at the end of each DPN for a round. Then after a few more rows, you could move the gap two round two more stitches by doing it again or move it back by working to two stitches before the end of the needle and slipping those on to the following DPN each time. For magic loop, shift the point where you divide your round.
Don't forget if you need any help with your knitting, my one-to-one knitting therapy service could the answer. Get in touch.