There are default directories that ProSeries uses (example: C:\Prowin21\21Data), or you are clearly able to change directories to any place you want.  I never use the default directories as I want all my computer data under the Documents folder.  I create a 2021 year, 2020 year, etc.  Then within the ProSeries program under the File Menu you have to Change Directories to tell ProSeries where to look for the current year and prior year data.  I do this as I use multiple forms of backup and it's just easier for me to tell Carbonite (online backup) or other software to just backup the entire Documents folder rather than having to pick and choose what directories in the computer to backup.  Your situation may be different due to networking, stand alone, etc. issues.  I've just NEVER had a problem doing it this way.