I love knitting winter hats for my friends and family, but tend to make them a single color when using circular needles because when I get to the end/beginning stitch, there is a offset which is fairly noticeable when going from one round to another. What technique can I use to make this offset disappear?
The technique is called a “jogless jog”. There are a couple ways to do it so here’s some links you can try out and see which you like best. They aren’t perfect after all knitting in the round creates a spiral, but the jog is less noticeable. 
See if this video helps. It has rather a long intro but useful information. You can minimize the jog and blocking will help too.