Circular pattern and two colors

I have a new bag pattern that is on circulars (which I’ve done for blankets) but it tells me to work a contrasting color for 4 rounds then main color for 4 rounds. How do I do this shift back and forth. It repeats mc for cc several times. thanks so much!

When you get to the first color change, just start knitting with the new color, but don’t cut the old yarn.

As you get to the beginning of the next round, put your working color under the strand of old color so it gets carried up. Then when it’s time to switch back, your strand is waiting for you.

Thanks so much. But I’m slow…and confused - you wrote: “put your working color under the strand of old color so it gets carried up” How would I carry up the contrast color without having it show in the pattern?

I think what Ingrid is trying to say is to drop the old color and let it hang (do not cut it) then pick up the new color from underneath the old color so that they kind of twist. The old color should lie across the base of the new yarn thread. You will not be working with the other color (for example Color A) it will stay in the loop of the second color (Color B) as you knit your stripes, then when you need it again simply pick-up, cross, and begin knitting the next series of stripes. Similar to the twisting done in stranded knitting. I hope my explanation has not confused you more.

Here is a nice graphic picture: