Do you mean that you are forgetting to increase/decrease at the right points? As mentioned, stitch markers will help, as will a good row counter.

Of course, you will still have to remember to increase your row counter at the end of each row. I have a row counter I keep hung around my neck, so it's easily accessible. A physical row counter (as opposed to an app) is better for this. I really like this cheapo one: https://www.amazon.com/Clover-Knitting-Stitch-Counter-Kacha-...