they have really small drivers, so as a result, they can't move a lot of air.
if they're seated well, they seal against your ear, so there's only a small volume of air they have to move which the small driver can do well.
If they're not seated well, too much sound pressure can go around the outside, leading to weak and tinny sound. changing EQ won't fix this, since it has to do with the physics of how sound behaves in your ear. It might make it "better" but it's not correcting the problem, and could lead to damaging them since you're pushing them harder than they were designed to go.
There are guides online about how to get them in properly.
there's also not one specific way to put them in that's guaranteed to work. Some point down, some forward, some in-between. you might have to play around with positioning a bit, as the shape of everyone's ears are a bit different, so what works for someone else might not work for you.
there are some skins you can put on them that might help make a better seal. But I believe most if not all require you to remove them to put them in the case.
It's possible that your ear canals are too big, or shaped in a way that won't work with them at all.
I personally can't wear them (or the APpros). I use Powerbeats pro, since they have a hook, and don't end up on the floor after I take 3 steps, and I can still get the benefits of Apple's H1 chip. Even with the XL tip, I sometimes have issues getting a good seal. I would much rather have AirPods, as the case for the PBP is way too thick to comfortably stick in a pants pocket, and I'd love the noise canceling of the APP, but they don't fit me.
it's possible that you got a bad pair, but I'd find that more likely if only one side had the issue. I'm guessing the left and right come off different assembly lines, so the chances of randomly getting 2 bad ones in the same box would be pretty pretty low.