You just have to practice with the method. You cant just expect to learn another language in a day and be fluent in the language after practicing for a day.

It is about muscle memory. When you first learn how to do a task correctly, you might do it even slower than when you were doing it incorrectly. With time and focus on the proper technique, however, you learn to hit the proper keys without thinking about which keys you are pressing, and that is when the speed really begins to pick up. If you're typing at 20-30 wpm at 95% accuracy, slow down a tad and shoot for 99% accuracy. Then, practice at that speed over and over. Soon, you'll realize that you're creeping up in speed without even trying. Within a few months, you'll be way past 40-50 wpm with very good accuracy.

Accuracy > speed
You should be proud of 99 % accurate typing with the speed of 15 wpm than 50 wpm with only 92 %. Lower accuracy than 97% is no use.

I know what you mean it happens to me all the time. What I was recommend is after you're done practicing and you try to test yourself, type fast But slow enough to be accurate to try and reprogram your fingers. After having enough accuracy practice then try to type as fast as you can.