thats definitely not a green terror.
in my experience, the whole moving the decor around doesn't do much. if a fish is going to be more aggressive than the other fish, no amount of moving things around will stop that.
as already stated, fire mouths are all talk. i would take his aggression as a good thing haha. eventually the jack dempsey and texas cichlid will be much bigger than him. you're gonna want him to keep his little attitude if he going to stand a chance with those guys once they're bigger than him.
if anything, add more plants to cause more breaks in sight.