In circular mode you can't decrease at the machine (as far as I know). However, if you want, you can decrease by hand (cast off by picking up the loops with waste yarn, don't cut the main yarn because you will continue to knit with it).
Hi Alina, thank you so much for this video. It's very helpful and informative. I'm new to knitting on a machine. I just brought the sentro 48 needles machine and my question is, can you knit a baby hat on it if the gage and number of stitches is the same? How can the same machine knit adult and baby sizes?
Welcome to the knitting machine family! You can make different hat sizes with the same knitting machine by adjusting the gauge and the row count. The tension of the yarn changes the gauge. Personally, if I knit with yarn Medium 4 for an adult hat, I use moderate tension (middle hole from the yarn guide); for a baby hat I use tight tension (I place the yarn in the smallest hole, or I hold it in my hand). You have to change the row count as well. For an adult beanie you knit approximately 90 to 100 rounds, for baby you knit only 60 rounds. If you want o slouchy hat you knit more.