Setting save location

I place documents in folders by their purpose. e.g. VolunteerWork, ComputerClub, Family, School, etc. etc.

I want to create a batch file called Writer in each folder that will set the open and save location used by LibreOffice to the current folder and then open writer.

I need to know how to set the location. Is it an environment variable or modifying a file or a command line parameter?

Thank you.