Help with all in next st;

I taught myself how to knit by watching Grandma and want to do a stitch I didn’t see Grandma do. I’m making an afghan and the pattern stitch is *(K1, YO, K1) all in the next st; sl 1 as to purl, K2 tog, PSSO; rep from *. I’ve doing something wrong, decreasing 2 by K2 tog and PSSO while only adding one stitch with the YO, each row decreases in stitches and my afghan becomes a triangle. Can anyone help me understand how to do this pattern without decreasing my stitches. I’ll be doing the happy dance when I get the answer. Thanks,

The k yo k into one st will add 2 sts to make up for the double decrease. Knit into a stitch and leave it on th L needle, then wrap the yarn around the R needle and knit into the same stitch again. You had one st, now there should be 3.