I'm a beginner singer who wants to get it correctly. I've seen quite a lot of videos explaining how keeping the larynx neutral while singing is crucial, but not a lot of the techniques they teach work. I've so far tried the lips trills and making a woofey sound, and none of those works. It's just impossible for me to keep the larynx neutral while trying to sing high notes. I don't know if it's because I'm used to singing and moving my larynx or anything else that makes it impossible to keep it still while singing. Could anyone tell me how I can get rid of this bad habit? Thank you!
The idea is really more that you shouldn't be tensing your neck muscles when singing high notes or depressing the larynx when singing low notes. It's going to move in either case, so that's why we watch it as an indicator of bad technique.
So, when singing high notes, instead of focusing so much on the larynx, try to become aware of the muscles in your neck. If your technique is bad, you're probably using them to constrict the air passage when singing higher. This should be pretty obvious and easy to feel.
Next, you'll need to experiment with allowing the pitch to change while keeping these muscles completely relaxed. This will take lots of time and practice. Key things to be aware of:
These points are actually relevant to nearly all instruments. Excess tension is a VERY common problem in instrumentalists, but in singers it can be directly heard in your tone.
The additional point to be aware of for vocal technique is the position of your soft palate and oral cavity. I'll link to my answer on a different question where I go into this in detail.
So to sum up, make sure you're not constricting the neck and throat muscles to sing higher, use good supporting technique (lots of breath support when going up in pitch), and localize musculature tension only where required (muscular control of the vocal cords themselves should be as subconscious as possible).
It would be very useful to see a singing teacher who will help you with your entire posture and body use as well as specific techniques for the obvious areas. Many singers also take lessons in the Alexander Technique, which I did for several years. This technique helps the old, bad habits just fall away and you learn to fall into a neutral, balanced position for any activity. Some people adopt a posture when they sing, or when they reach high notes, that gets in the way of a good sound and can actually damage your voice. Interestingly, I've been trained to be extremely cautious about body use, and to model a very natural, neutral posture, when teaching children to sing. As you are new to singing, this is the best time to learn how to use your whole body as your instrument and develop a healthy, natural technique.