They spit the pellets out because you keep feeding frozen foods. They also appear to be grossly overfed, that puffed out gut is from too much food, not excess protein.
You either train the fish, or allow the fish to train you.
It's really that simple.
It's not rocket science, but there is some skill involved, and in some cases you need to have great patience, and be smarter than the fish.
Stop feeding frozen food, then once each AM offer them a few pellets that have been soaked in frozen blood worm juice. Lightly soak the pellets with bloodworm juice for 4-5 minutes before feeding using a small pipette. Just enough to cover the pellets to slightly soften them up. Within 7-10 days no more need to pre-soak.
Using bloodworm juice as a stimulant is a natural for your fish, the smell triggers a feed response, the pellet becomes more palatable because it is softer, and the taste/smell is very familiar to the fish. Even if the fish resists it initially, usually they will start picking at the pieces of pellet at the bottom of the tank. Once they start even eating small pieces off the bottom, you are on the road to success. Once they are eagerly eating the presoaked pellets slowly decrease the BW soaking until you are eventually feeding the pellets directly out of the jar.
I've lost count as to how many wild caught fish I have trained to eat pellets over the years. Ditto to several juvenile flowerhorn imported from Thailand that had been raised on a strict diet of fresh BW, and had never seen a pellet in their life. Juvenile fish are generally very easy to convert to whatever food that you want. Most take to it straight away, others are more stubborn and require some serious effort.