Just made changes to those in bold according to the new folder location.
/mnt/HD/HD_volume/folder
volume = a2 for Volume_1 (HDD1) or b2 for Volume_2 (HDD2)
folder = exact folder name (case sensitive)
For example, let said you created a new folder call BTdownload in Volume_2 so the new absolute path would be /mnt/HD/HD_b2/BTdownload
Hope this help.