I'm not going to comment on the second one as he was already pretty tense in the first one, but one thing that would really improve your scores and get your horse a bit more relaxed and thinking is really sticking to your lines and riding figures accurate down to the millimeter. Don't let him drift through your leg and kind of cruise through the corners. Yes, I know what it feels like on a ticking bomb of a horse, but as soon as he learns to accept and listen to your legs for direction you're going to have an easier time with his focus, and a bonus is your scores go up.
The other thing that really needs focus put into it is the neck position. He uses his neck for everything, every walk and trot stride he is throwing it around for balance and in the transitions it is even worse. There are a few things which will help this, the first is working in long, lowly attached side reins on the lunge. The second is as he relaxes his neck will naturally come down. The third is related to the second as he relaxes you will better be able to start the "engine" behind and get a more forward reaching stride and his neck will lower. The final thing is working on the lateral suppleness which will come with time, but right now, especially in the walk which is almost completely lateral, you should focus on a lot of dramatically bent leg yeilds where he really needs to yield his ribs to your inner leg and move over. Developing the submission this way will also help you to get it when you are riding "normal" lines (and riding on your lines, and your figures exactly to the millimeter).
Overall, those are respectable scores for your first time out on him, and of course the judges comments as well will hopefully give you lots of things to work on for next time. That's the great thing about dressage - we never get 100% but we are always striving towards it!!
They say money doesn't buy happiness -- well happiness doesn't buy horses!