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 Samoyed, watch their thirst, their eyes and their coat. Drinking and weeing much more than usual, or losing weight while eating well, can be diabetes. A red, cloudy or squinting eye can be raised pressure inside it, which needs seeing quickly. A thinning coat and a slower dog can be their thyroid. Bloat (GDV, a twisted stomach) is most common in large, deep-chested dogs, so skip walks and hard play shortly before and after meals. A swollen, tight belly, retching with nothing coming up, sudden restlessness or drooling is an emergency: contact your vet now. It is easy to put any of it down to the heat, but with diabetes or the thyroid weeks matter, and with an eye, hours do.
They'll keep smiling in the lift. If the smile comes with a squint, call your vet that day.