Help! I'm a new knitter and my hat pattern says to "change from size 7 needles to size 9." Does this mean I start using a 9 on my right hand needle for the next row--or do I take all of the stitches off the 7 and put them on the 9? If the latter, will they fit??
You have the right idea. Instead of continuing the next row with the same size 7 needle you have been using, change it to a size 9. Then then next row, change the remaining size 7 for a size 9.
The first row may be a bit tight going from one size to the next but after that, it will be fine. This technique will give you a tighter portion and a looser portion of your project. It is frequently used in ribbing.