The default instance is your instance (local). In the setting you can change this to all. Under user settings.

There will likely eventually be a way to migrate your account just like mastodon, however kbin is a different platform altogether and you would need a new account there.

Nope, so far the app will log into the last account you’ve used.

I’m sure there are a lot of “previous state” saves it’s missing to make a better experience. I always have to reset to Subscribe: New Comments for the best experience.

Someone made this cool tool for Mastodon that lets you switch. Maybe someone will do one for Lemmy soon.

https://github.com/stefanbohacek/mastodon-tools

So can I log into Jerboa with my kbin.social account or not?
Edit: Turns out I can’t. Jerboa seems pretty useless to me if I can’t filter out the unwanted instances.