Editing a library in the Cloud, change an address with code.

Hello,
I am using an MS5611 which can be addressed at 0x76 and 0x77.
Locally I can change an address in a library but I cannot see how to edit a library .cpp or .h file on the cloud. Are these editable in the cloud?
Secondly, I recall there being a couple of lines of code to carry this out in an ino script something like 'if not 0x77 then 0x76'. I have forgotten.
Thanks

Why are the library files in the Cloud and not local ?

It is my first use of the cloud for arduino and i assumed that all files including the libraries would be uploaded for how would one program remotely so that theoretically one could go into an internet cafe and continue programming in the cloud.
I will check.
Thanks