Welcome to the community, and thank you for taking in Koda! I have had my Senegal Kane for about years now, and he definitely has a much different personality than any other species of parrot I've owned or interacted with before. They really do tend to be one-person birds, and they also seem to be a lot more timid than other species as well...Even Kane, who I got when he was 13 weeks-old and was hand-raised/hand-fed, was very timid at first...It was like he attached to me right away and slept in my hoodie during the 9-hour drive home from his breeder's house, so he was used to people and wanted to be held by someone (just a little tiny baby), but he wasn't thrilled about me at first. It took him a few months until he interacted with me like my other birds do, where i could handle him however I wanted to, where he'd fly to me when I called him, etc. So if you've only had Koda since Saturday I'd say you're doing very, very well...
It's a marathon, not a sprint...That's what you have to remember, though I'm glad you've got patience and time...I'm going to assume from Koda's personality and interest in you and what you're doing already that he was probably a hand-raised baby bird, and that his original owner, the elderly woman, probably handled him regularly and was "his person", meaning he was bonded closely to her...So now that she's gone, he has to start-over and again learn to give his trust to someone else...And it will happen, it's all about time, patience, and spending as much time as you can near him...
Passive-Interaction is as importance as direct-interaction, meaning that just having his cage in the "main room" of your house, meaning the room you spend most of your time in when you're home, is going to be a huge deal..Usually this is the living room, TV room, Den, etc. So even when you're simply watching TV, reading, on the computer, playing video games, eating your meals, etc., just having him in the same room as you is going to make a huge difference in making him comfortable with you. A lot of times people will put their new bird's cages in a spare bedroom or back room they designate as being "the bird room", and this not only doesn't help in the bonding/socializing process, but it also tends to cause the bird a lot of anxiety and insecurity, because they can hear people are home and out in the living room doing whatever, but they can't see them...And after-all, they are "flock" animals, and you're his "flock" now. So just having him in the same room with you will help tremendously...
****Regarding His Cage****
What you need to understand about Koda's cage is that it is the only familiar place he has right now, even if it's a brand new cage, it's now his "territory", and his "safe space"...and if it's the same cage he was in before coming to your home, then it's an even bigger deal...So a lot of the time they do become quite nervous and even upset and aggressive whenever you put your hands, face, etc. inside of their "territory", even once they've bonded with you and love you to death and allow you to handle them! Both Kane and my Quaker Parrot Lita are both extremely territorial about their cages, and I brought both of them home as hand-raised babies who were 13 weeks-old and 9 weeks-old, respectively. Kane just turned 2 and Lita is now 3 and a half, and I can handle both of them however I want to, they both fly to me when I call them, the both take naps on my chest, etc., but whenever I put my hands into their cages, even to feed them or give them water, they both get very defensive about it...So even to this day, whenever I open up either of their cages to let them out, as they are all out of their cages any time that I'm home, I have to just open-up their cages and let them both come out on their own, which they both do immediately...And there is a huge difference in the way that they act in and right on the outside of their cages...With Lita, the Quaker, I will open her cage and she'll immediately come to the open door and sit on it, and from there I have her step-up on my hand and she's fine, but only once she's on the open door...With Kane, the Senegal, he doesn't like me to give him my hand until he's climbed up on top of this cage to the perch that I added on to the front-outside top of his cage (it's over his door on the outside of his cage)...
So that's his routine, I open his cage door, he comes right out, climbs to the top of his cage, then walks out onto the perch and walks the entire way to the end of it, as far away from his cage as he can get, and only THEN does he climb onto my hand/shoulder...So he's extremely possessive about his cage....I actually open his cage up and have him come out onto that outer perch before I put his fresh food and water inside his cage! We worked-out a system that works for him and I respect that. He usually will climb up to the exterior perch and then on his own he comes over onto my shoulder while I'm putting his food and water into his cage, and then he'll climb back onto the perch and then back into his cage to eat, then he'll come back out, up to the perch, and then he wants to be with me/on me, but if I just open his cage door and put my hands inside it to feed him or I just stick my hand in and ask him to "step-up", he'll typically "beak me" while making his "I'm not happy at all" soft growling noise, and he'll reluctantly step-up onto my hand...as soon as he's outside of his cage he's fine and happy to be out and be with me, lol. It's like that threshold to his cage interior is the line that I have to respect, so I respect it and we're both happy...
I'm going to assume that once Koda settles-in and starts to become more and more familiar with you, if you open up his cage door, let it open, and you stay in the same room and just continue doing whatever you're doing, he'll eventually start coming out on his own, especially if you have some kind of floor or table-top stand for him to go to, that will also be "his territory". It's just going to take some time to get him to feel comfortable enough with you to want to come out, and that will happen by simply spending as much time as you can with him/around him, even while he's inside of his cage...But you can probably assume that the way he acts inside of his cage is going to be very different than the way he acts when he's outside of his cage, which is perfectly normal, and is just something that is best to respect.
