Q: Anytime I try to add any single album or song to my iPhone, iTunes decides to try and sync the entire music library to my phone. How do I fix this?

Greetings LuisM1234,

Welcome to the Apple Support Communities!

I understand that you are trying to manually sync a song or album to your iPhone from iTunes, but your entire library ends up syncing. To manually manage content on your iPhone, please follow the instructions in the attached article. If this is the process you are using and it is not working, please let me know. 

Manage content manually on your iPhone, iPad, and iPod - Apple Support

Cheers,

Joe