Hello @BubblyRomeo! It is true, like @green_copper said, I have a life outside of Mbin, but I have now seen your comments (please try to keep a nicer tone though). I'll try to help you where I can.
Interstellar uses kbin.earth as the default instance, mainly because they were both created by me. But you are most certainly not forced to use kbin.earth with Interstellar, you can add/switch to any Mbin, Lemmy, or PieFed account by going to the settings. And once you have added a different account (and switched to it), you can even remove the default guest kbin.earth account from the app.
As for your kbin.earth issues, are you saying anytime you try to log in, you get an "email not verified" message? I'm actually surprised that's happening just because usually if an account on Mbin is not email verified yet, then it wouldn't even let you make comments or posts yet. And for the 2FA problem, I'm not really sure what the issue is there, I tested it just now and was able to enable 2FA on my own account just fine; is it possible your phone's (or whatever device you have the 2FA app on) clock is slightly off? Which could definitely cause issues for TOTP based 2FA.
You shouldn't have made kbin.earth the default instance when signing up from the Interstellar app if your instance has some serious security issues!
kbin.earth is just an Mbin instance. The only thing I've really customized is the kbin.earth branding. If you think kbin.earth has security issues, then you probably shouldn't use Mbin at all. That said, if you'd like to migrate to a different Mbin instance, Mbin doesn't really have a good way to do that. If you have tons of magazine or user subscriptions, then you could try using Interstellar's account transfer feature, but otherwise, you'll just have to manually copy over your settings to your new account.