Hi there,
Just read your requirements and i am sure that i can help you on this project. I can redesign and modify your application, i can change color, logo, package name, Youtube Api keys as well.
I can also change app design as per your requirements , as you said you have design ready. I have quite good experience in mobile application development , you can also check my profile to understand more better about my expertise.
Let me know if you're ready to working with me.
Looking forward to hearing from you.
Thank you.