I've been playing around on the violin for a couple of months but I can't seem to figure out vibrato. I've tried watching a bunch of YouTube tutorials, but they only seem to work when the violin is in guitar position and when I put it up under my chin, it is really awkward trying to do vibrato how the videos tell you to. I really want to be able to play with vibrato because it makes the music sound SO much better.

Vibrato comes with time and practice, being that you're a beginning violinist don't worry about it just yet. Try practicing finger warm ups and getting comfortable with a slowed down movement of vibrato until you develop the skill. You have to make the joints in your fingers, wrist, and elbow loose and it will help make the movement easier.It's also sometimes easier to start working on vibrato in third position. It's one of the hardest parts of playing violin so don't feel badly that you can't yet hope this helps.

I would agree. Trying to learn vibrato early on may actually lead to the development of poor posture and bad habits as you put all of your attention into learning a new skill. The best thing to do is get really good at the basics before you move on. In my opinion, the best thing to do would be to find a teacher to help you get the basics down and then help you move on to vibrato. It will be so much easier to learn when they can show you how to do it and tell you if you are doing it right or what you should change.