Library swapped external HDD’s

Hello,

I have a himedia Q5 where Kodi Pro 16.1 is on. Because an addon service from the seller, I can not yet updated kodi to 17.1. On my Q5 are two external hard disks connected, one for movie’s (sda) and one for series (sdb).
It all works very well however I only suffer that after each boot the kodi library mixed up my hard disks (movies sdb and series sda). In the library of my Q5, after each start, are the hard disks at the same position (movies by USB 3.0 and series by USB 2.0). After each startup of kodi I’m busy to get the library good again, which is a lot of hassle!

What could be the problem and what could be a solution?