Linking iPhone and laptop

I have an account on my laptop with the user name Warrenhamilton28@gmail.com. I want to link it to my iPhone I may have inadvertently opened a new account on my iPhone just using my name Warrenhamilton. When I open my phone to Musescore it shows just my name, hence the reason I think I may have opened two accounts without realizing it. Anyway, I want to make it so I have access to my saved laptop Musescore files.

2nd Question: If I download a new song on my iPhone will I be able to manipulate it (transpose etc.) just as I do on my laptop? THANKS