Retraining an OTTB

Question
Basiclly 3 months ago I bought myself an OTTB and have been in the process of retraining him but the fact that he is an OTTB and not just a normal young horse adds some interesting factors.

Basically he has bolted on me twice now and I need to learn to correct this as I don't really like going for rides all that much. I've been told tons of things that could help this but I want to know what your suggestions are. We have been working alot on a lounge line and working on commands which he seems to do fine with but when I get in the saddle its like he forgets. Now he has never bucked or reared on me just bolted. Also he holds his head very high and I'm trying to get him to relax it for me. I was told to possible use a bit of a harsher bit to keep him from taking off and to start working with lowering. The problem I see is I don't wanna fall pry to needing such a device to ride. Right now he is going in a D ring snaffle and I ride him english. I just had his teeth and shoes done so its not that and he was checked for pain in his legs and back nothing.  I have been brave enough to ride him out in just a halter and he did great to the point were I considered a bitless bridle but I can't show if I use that.

SO any advice you can give me would be very helpful cause if I don't get his bolting issues under control my parents want me to sell him cause they don't want me to get hurt. Thought he's a very sweet horse other then his bolting issue.

Answer
HI--- WELL WHEN YOU BUY A HORSES THAT WAS PREVIOUSLY TRAINED BY SOME ONE ELSE , THEN HE WILL HAVE HIS MIND ALREADY SET ON CERTAIN THINGS. IT WAS GOOD THAT YOU DID CHECK HIS TEETH AS THAT IS ONE OF THE PROBLEMS WITH BOLTING. THEY GET SHARP EDGES ON THEIR TEETH AND THEN THE BIT HITS THE TEETH AND CAUSES THE HORSE TO REACT. A VET CHECK WAS ALSO THE RIGHT THING YOU DID , LOOKING FOR SOME LAMENESS.  I DID HAVE ONE HORSE WITH A CUT ON HIS TONGUE AND THAT WAS A PROBLEM FOR QUITE SOME TIME , TILL IT WAS HEALED UP. I WOULD GO WITH A MILD BIT AS YOU DON'T WANT TO IRRITATE HIS MOUTH. I FLOAT THE TEETH EVERY 6 MONTHS AND CHECK FOR OTHER MOUTH PROBLEMS ALSO. YOU COULD TRY A PAIR OF FULL CUP BLINKERS TO KEEP HIS MIND ON HIS BUISNESS, SOME RACE HORSES ARE VERY NOSEY AND TEND TO NOT KEEP THEIR MINDS ON WHAT THEY ARE DOING. A FIGURE EIGHT ALSO GIVES YOU SOME MORE CONTROL , AS IT KEEPS HIS MOUTH SHUT WHEN RIDING HIM YOU CAN ALSO HAVE A PHYSIC COME TO THE HORSE AND READ HIM FOR YOU. THEY SEEM TO KNOW WHAT IS BOTHERING THE HORSE AND CAN FIND THE PROBLEM FOR YOU. IT MIGHT SOUND FOOLISH, BUT I HAVE HAD IT DONE MANY TIMES AT THE RACE TRACK AND HAVE FOUND IT VERY USEFULL.  HOPE THIS HELPS YOU  GOOD LUCK ed hess