IMHO Don't USE the one Calibre creates for books. My main Library is called
Main 
. If I ever see another name up there in the Windows Titlebar, I know something went wrong (very rare config folder? issues)
rename your real Library folder using the OS (Calibre NOT running )
then start Calibre: on the Library Icon: Create/Switch: USE EXISTING:<navigate to your new foldername> OK
This is one of the few cases you can touch a folder name in Calibre without causing major damage (the folders name IS the Library Name) (and yes, having 6 Calibre Library's is valid (and a quick way to insanity
)
BTW don't let W10 confuse you (too much). It has a section called 'Libraries'
This is a Logical view that may contain a merged VIEW of the contents of various other (real) folders. eg Documents (yours) and Public Documents