Can't select boot options on grub

so basiclly i'm using Zorin 15.3 lite 32-bits and it's pretty good except i can't select boot loaders in Grub, i type the arrow keys but it didn't work, someone please help me pls

You may need to ensure that USB is enabled in your BIOS EFI settings, treating your USB Keyboard as a PS/2 Keyboard.

i'm using legacy, how to enable it

It varies by manufacturer, or even if the manufacturer has included it at all...
You should be able to access your BIOS settings by tapping F8 or F10 or F12 at boot... From there, explore your settings.
You may try a net search using your Make and Model computer in the keywords.