Brother DCP-8020 - Manual (Page 169)

USING THE WINDOWS ® -BASED BROTHER SMARTUI CONTROL CENTER (FOR WINDOWS ® XP) 10 - 14
Custom
Scan to File—These buttons have been pre-programmed for the
Scan to File feature. You can change the configuration of each of
these buttons to meet your specific requirements by right-clicking on
a button and following the configuration menus.