How to update properties (library path) to symbol definition in PCB Editor?

I'm examining a symbol in a *.brd file, and I find the following line: 

"Properties attached to symbol definition LIBRARY_PATH = M:/afx/Board_Projects/LIBRARY/ALLEGRO_LIB/symb ols/ff1760_smd.psm"

 But my library_path should be different; how do I update this information?

Thanks!