Do I have to change banks when I sign up for Lunar? 

That’s entirely up to you. You can choose to be a customer both places, or close your current bank account and solely be a Lunar user. 

We would love to have you as a private user as well - in Lunar it’s not mandatory to have a personal account in Lunar to use Lunar Business. You can use Lunar Business while having your private account at your current bank as well.