So I've been playing guitar sitting down since I started about a month ago. Now I'm trying to play standing, the problem I have though is that the neck keeps drooping down, so I have to hold it up while playing. This is hard enough while playing riffs, and impossible for me to play any sort of melody. This surely isn't right, is it? I've seen some videos of youtube of people playing standing and even when they let go of the neck during a pause in the song their guitar stays in a fixed position with the neck pointed slightly upwards how it should be. However, when I let go of the neck it just drops down. I've tried adjusting the strap, it makes no difference, any advice?