Don't squeeze your lips too hard to play high notes, increase your air flow from your mouth, the higher speed of air flow, the higher vibration of your lips, the easier to play high notes, just like how people tend to scream so loud when they sing high notes
Btw master one instrument first before starting another one, they might look similar, but the skills are different
Dang, you really nailed your username
Don't squeeze your lips too hard to play high notes, increase your air flow from your mouth, the higher speed of air flow, the higher vibration of your lips, the easier to play high notes, just like how people tend to scream so loud when they sing high notes