Some birds are picky eaters. If your bird is a picky eater it will sometimes eat foods that it sees you eat. Also, get your bird to try new foods by handing the food to them when they are someplace they are happy such as a certain perch in their cage or out of cage on a playground, etc. Never starve your bird into eating new foods. To get your bird to eat, give your bird his favorite foods, but also a variety of different foods.
Birds are intelligent beings.
If you give them the same old thing day after day, it's bound to bore them. Don't be afraid to offer seed, as long as it isn't the main meal. Offer up the bird pellets as well, as they have essential nutrients. You can give your bird a vitamin, mineral and amino acid supplement. Add this in a powder or liquid form to whatever your bird will eat.