I have an 18 month old QH and he is almost 14 hands I have started him under the saddle my vet told me that it was fine and I was wondering what bit I should use I have a regular snaffle bit on him but he runs through it and he won’t turn at all could you give me some advice please thank you, Katelyn

Did you start by ground driving him and teaching him how to walk, trot, and lope, back and halt. If not, go back and redo your training by this method and he will stop running off. Do not use anything other than a snaffle. He is not ready for more bit at this age. If you do not know how to ground drive, you can get some help from a qualified professional. It is something you will need help with if you have never driven a colt before.