Hi Sista Aisha
I used to get my hair braided and if the hair was Human hair being put in As sister Poetic said use the crazy glue. You can also try, if the hair is synthetic, dipping the ends of the hair in hot water. This heat shrinks the hair and seals in the braid. You can also(if you have time) tie 2 small strands of the same braid you are working on into a small knot. Good luck in taking it out thought its a lot of work unless you cut it out
Happy Hair doing
Queen Abena