Couple of different ways:
You can create a thread bump that you slide the bead onto, affixing it.
Or, you can tie on a little strip of wire that extends over the hook eye, previous to threading the bead on. Slide the bead up, then pull the wire over the top of the bead, then secure the wire with tying thread. This process lashes the bead securely to the hook shank.
Also, make sure you put a bead on that is properly sized to the hook, so it doesn't slide over the hook eye.
Hope this gives you the answer you were looking for.
Brookie