Some of this is not a training problem, and treating it like one wastes time your dog may not have. If they are distressed when you leave, if they growl or guard their food, their toys or you, if they are frightened on the lead, or if anything about them changes suddenly at any age, contact your vet the same day. A tip from a website, ours included, is not the answer. If it cannot wait, contact your nearest emergency vet now.
With a teacup Yorkie, almost anything that looks like behaviour can be their body. Quiet and shaky can be low blood sugar. A puppy who is slow to grow, sick often or strangely dull can have a liver problem. A honking cough is their windpipe. Limping after a jump can be a fracture. If they are weak or trembling, contact your vet now. Bloat (GDV, a twisted stomach) needs the same speed: a swollen, tight belly, retching with nothing coming up, sudden restlessness or drooling. It can happen in any dog, though it is most common in large, deep-chested breeds.
With luck, they'll learn to wait at the edge for a lift. If they won't put weight on a leg, call your vet straight away.