Boot MacOS on external disk - default

[Demovx]

Hello!
I have a qestion.

I have iMac with usb external disk with MacOS High Sierra. ( No APFS ).
When i power up imac, i see black screen. After 10 seconds, the apple logo appears and the booting from the external usb disk. All works fine but i need boot default from external USB ( save the 10 seconds ;p )

My internal disk is clean - no MacOS On this drive.

Can i change in terminal or other app this setting?

In my settings> start disk> i have only my external disk. ( MacintoshHD macOS 10.13.2).

 

[m4v3r1ck]

But did you SELECT - flag / highlight - your USB as macOS startup disk, otherwise your Mac will still do a search on all internal/external HDD/SSD ports.

Cheers

 

[Demovx]

But did you SELECT - flag / highlight - your USB as macOS startup disk, otherwise your Mac will still do a search on all internal/external HDD/SSD ports.

Cheers

Xd?

And second screen on my terminal