During placement of Standard Parts into an assembly you have the option 'Copy to Working Folder' in the lower right corner. That option in the PartFinder menu is sometimes checked and greyed out so it cannot be unchecked.
You cannot uncheck this option when placing pipes or frames but you can still choose to use the assembly folder as the working folder which is the option next to the inactive 'Copy to Working Folder' option.
Hardware/Software Configuration Platform: INTL64
OS Version: 1064