Cockatiel advice needed please!!!!

My cockatiel, Bartleby, seems to be worrying me. I got him a little less than two months ago. We're working on our trust and so far things seem to be going well. He can eat out of my hand and learn whistles I teach him but nothing else yet. So far that's good. What's concerning me is that when he's in his cage, he only sits in two spots and that's it. I NEVER seen him in other spots of his cage and I always watch him. His cage is also really big with lots to do but he doesn't go anywhere near them. He'll either sit on the perch right in front of his food dish, or on top of the wooden toy I have on the side of the cage. That's it. I just have a little concern on why he's not exploring his cage. He doesn't play with his toys, he doesn't explore around, he doesn't check out the treat dish of fruits and veggies. NOTHING!!!!! He just eats his seeds (i'm going to change his diet soon btw), drinks, or sits around. Any advice on what might be wrong? Help my entertainment-deprived cockatiel.

I had this, until I found 'foraging'. I hide treats ( sunflower seeds, sprouted seeds, leaf lettuce) in wrapped up paper or toilet rolls and hang them up around the cage. It works a treat! Sprouted seeds are very good for your bird. I soak the seeds overnight in water then drain them and leave them for a few days. Gum branches are excellent also. I get a fresh one once a week. I got my budgies to eat greens by hiding carrot tops ( the green stuff ) in the leaves. After a few minutes my budgies were tucking in. It still tokk me a few months to extend their diet more, and I still am giving them new things. When Thimble, Lexi, Chubba Chubs and Dude ( now named Jiggles by new owner ) were nestlings Marigold and Skye ate everything I put in their dishes, so they grew up on a healthy and nutritious diet.
Hard boiled egg
Carrot
Carrot tops
Corn
Rice
Leaf lettuce
Apple
Seed mix
Sprouted seed
Seed grass
Are the foods my budgies usually get.

Great! Thanks. I know Bartleby is crazy for the jalapeno cornbread I make for him and millet spray. I'll be sure to hide some of it around his cage if it doesn't crumble up! He's on a seed diet. I actually plan on changing it to pellets next week. I only found one breeder in my area and had him on a seed diet already but, I actually put pellets in his dish with the seeds and he eats them, which is good. My keet S'mores is on a pellet diet since I had her for about 3 years, so she'll pretty much eat anything (especially pizza!!! her favorite human food ever) So, on my list of things to do: 1-Change Bartleby's diet and 2-Hide cornbread and millet around the cage.