The newest leaves look fine to me. As for the yellowing leaves, it's not getting enough sunlight. It takes energy maintaining "x" number of leaves, and when it can't meet that demand, it will shed older leaves in order to conserve what little energy that it is getting. When your plant begins shedding older leaves, I would recommend leaving the leaves alone. At least until they have turned completely yellow. The reason leaves turn yellow before they die back is because the plant is reabsorbing all of the chlorophyll and other nutrients back into the plant, to reuse in other areas; rather than having to start from scratch. It may not look all that appealing, but it's just a natural process that all plants go through. Sure, you can remove those leaves prematurely and your plant will still live, but why let that chlorophyll and nutrients all go to waste, when they can be used to help benefit your plant in the long run? Just some food for thought.

I've seen them at the big box stores here in Austin. I've actually got one that the squirrels keep trying to store nuts under that I really need to relocate. It dies down every winter and is just now starting to leaf out again. I would be happy to divide it if you are ever in the area (I'm totally assuming they can be divided?). Good luck!

Yours is slightly larger than mine. Mine is my first and I got it at a nursery in early June. I really like it. To me, the marks on your leaves look like shipping damage from the leaves being bent too much. The younger leaves yellowing could be just from acclimation to your new environment. The leaves pulling out and the new leaves that appear to fall apart - I am not sure what that could be. It probably all began with the lack of drainage you mentioned. Fungus gnats love moist unventilated indoor soil. I used to have a lot inside in the winter and none now in the summer. Others on this board can give you some more help than me. I've had a few indoor plants that began dying in early Spring. Then when I placed them outdoors and in the ground they ALL perked up. My banana had several treatments of copper fungicide even after being planted in the ground. It's beginning to look nice. Back to my M. Deliciosa - I place it outdoors almost daily in dappled sun and never in the wind. It's doing well. No issues. I bring it in when windy or if rain is eminent. I also back off the water. I only water when I can detect dryness by sticking my finger 1" into the soil. It's hard for me to not water like I do other plants. But I know they have aerial roots in their natural habitat and climb up trees. So their roots are exposed to the air. Here's mine when I got it on June 10: https://st.hzcdn.com/simgs/48e2ed860b1dde23_9-4068/home-design.jpg And here it is outside tonight - 3 new leaves have opened since buying it. It still bothers me to see the soil that dry. Those flipped over chairs around them filter the sun they get: (on left is Philo. 'Brasil, center is Pothos Epipremnum aureum 'Manjula')

Difficult to say what exactly is the cause. There are two easy to notice mistakes you did though: first, the plant is buried too deeply second, you should always water immediately after re-potting, otherwise the new, dry soil will suck the moisture from the old soil the plant was in. Either one, or both of these mistakes could be the cause, or at least contribute, to the yellowing. .