Mostly what others have said, I would just add that for now you should probably make a point of asking for him to stand still after he has worked down a bit, enough to get most of his excess energy out of him. Stack the deck in your (and his) favor and only work on standing still after he has a good long workout and can appreciate the benefits of stillness.
Obviously later that will change and you will expect him to stand whenever and wherever, but to start, make it easier on both of you.
And to start training him to stand still you need to focus on making the halt a reward. So for a few days/weeks/months (depending on his dedication and your frequency of execution) when it is his turn to wait in a lesson, instead of asking him to stand still (a battle you are not winning) go off and do some trot circles/serpentines/figure 8s/trot voltes/shoulder in, rein backs, turn on the haunches/forehand, etc. All things that are a bit physically hard and for sure mentally hard (and if you feel like you need more horse for the lesson, you can shift to mentally hard - shoulder in, rein backs, turn on haunches/forehand and so on so as not to physically wear him out). Then go back to the lineup just before it is your turn again and see if he is ready to stand still. The trick here is to time it in such a way that YOU ask him to go back to work rather than his patience expires, otherwise you are just losing a different battle.
You need to make standing still the reward, not the battle. Right now it sounds like you are trapped between trying to get him to stand still when he doesn’t want to (good luck with that!) or maybe walking off. The former battle he is winning, the latter is the wrong reward. If he’s not standing, he’s working! Just remember, work isn’t always about hard physical work, it’s about tough mental work as well. Always remember to start this exercise AFTER he has worked off excess energy. As he becomes proficient at standing after he is tired, then you can push up the exercise in the ride and ask him to deal with his natural impatience earlier in the ride, but not until he has mastered it at the later stages.
And last but not least, if - while he is standing - you notice he is shifting his weight from side to side (front or back) when he seems otherwise relaxed, he’s telling you he is uncomfortable. Some horses just are for a variety of reasons. If that is the case you owe it to him not to stand around (and to get to the root cause of discomfort if possible). In those cases I try to stay off the horse when waiting around for classes and keep him walking on a loose rein when waiting my turn (always allowing him to stop for as long as he wants).
ETA - for me personally I would not use the one handed turn. It can work but for my training process it becomes counterintuitive for my horse to equate that aid with halting, if only because the way I start turn on the forehand (not haunches as orig typed, DOH!) (as a precursor to working off leg/rein aids) is to lift the inside rein and only release when the horse does move his inside hind leg. So ultimately they equate an active inside rein/leg aid with a need to move the hind leg, which is pretty much the key to getting them to fill the outside rein. For me at least. Many roads to Rome 'n all that, but before using that response you need to make sure it isn’t in conflict with your larger goals.
