Them don’t use spurs or crop because he will Overreact
squeeze with calf not heel
Push upwards with you legs. Or use spurs
Lots of leg so he goes nice and round and also make sure to raise your hands and he should almost follow your hands as a guide as where to put his head and if he is not tense with his backend he will move freely into the contact extended trot😀Good Luck
Do you mean lengthen?
Trot poles are handy - set them at a distance that the horse slightly has to stretch over. Keep a rhythmic trot on approach and ask for the lengthen over the poles without increasing the speed.
When you do the posting trot when you go down you need to squeeze and also get a dressage whip and give a little tap.