Teen Bodybuilder 18 years old: Flexing

Just flexing. I really need to work on double bicep pose. Or better yet my decline chest cause my chest just disappears everytime I put my hands up. If yuh know a good exercise for decline besides decline bench. I like doing iso workouts so 1 side of my body isn't doing more than the other. And sorry for the audio cause copyright kept it bit it's saying it still has copyright so idk -_-