subtitles are not being saved next to the movie



Hello  ,
i  need  your  kind support  ,  i am using Kodi  installed  on  my xiaomi tv box ,  i  have  attached  my external Hard drive to xiaomi tv box ,  but whenever  i download the  subtitle  it  runs  ok  ,  meanwhile  if  i  closed  the  movie  and  opened  it again  i  cant  find the subtitle and  needed  to re download  it , even when  i try to search for  it  on  my  laptop  i can  not  find  it  in the  folder  next to the movie ! 
considering i have already  done the  permissions  in  my  tv box  and  in KOD  to save the  subtitle  file  next to the  movie  in the  movie  folder 

any suggestions or  ideas how to solve this  issue  please  ?