if you are not going to bother informing us as to What your hardware is
desktop
laptop
handheld
a VM ( kvm,Vmware,VB,...)
nor how you put Kali on a usb drive
nor if it is a usb2 or 3 drive
nor if there is persistance
there really is not much we can do
other than
#1
register on the Kali forum
http://forums.kali.org/
and ask there
mind you
the TARGET user of Kali can write the install guides and tutorials from memory
also you will NEVER LEARN anything about using kali from youtube
#2
please READ the kali documentation
https://www.kali.org/kali-linux-documentation/