SSD in Hard drive slot not booting up

Hello, I’ve recently installed caddy in my inspiron 17 5749. It seems like I’m having difficult time adjusting BIOS settings. New SSD is in currently original hard drive slot & old HDD is mounted with Caddy. It always says can not detect boot device, after cloning original HDD to SSD. However, I can boot up SSD from “Boot option” can someone help me what do I do to boot up SSD(which is in original hard drive slot) normally.