My horse is very soft/responsive in the arena and when we ride with another horse, but when I ride him by myself somewhere new, he seems really skittish and hard-mouthed. It'll take 100x more force to stop him than it usually does (usually all I have to do is sit down in the saddle and give a tiny bump with the reins to stop him from a canter in the arena and when we work out in the pasture at home). And he also basically ignores my cues neck reining, which he usually does very well at responding to. In addition, I literally have to hold him back when we're walking down the road or new pasture, corn field, etc. If I just relax and let go of the reins, he breaks into a trot and gets faster and faster until he's cantering (I've tried this; relaxed and didn't hold him back, and also didn't cue him on, and he kept getting faster and faster.). I've tried 1-rein stopping him when that happens, but we just end up doing 10 circles before he finally stops (which also doesn't happen in the arena or in familiar places, he usually does barely 1 before he stops).
And lastly, he always wants to run back the way we came from when I'm riding him someplace new.
What can I do? Help please!