I'm so confused!

Is the "Microsoft Account" at the upper right of an Office screen just used to determine whose OneDrive account a file is accesed from or saved to when using OneDrive?

There can be more than one account listed there.

If you are not using OneDrive, does it matter which account Office is signed into (eg. if the file is on the C: drive)?

Does every account listed there, require a license?

And finally, if there is VBA code in an Office application, does Environ("UserName") return the user signed into Office, or the user signed into the computer?