Hello @Fran,
At the moment passbolt does not support working with multiple accounts in a user friendly way.
When you want to switch users you need to perform an account recovery (by going to yourdomain.com and following the procedure).
If you want to be able to switch more easily between passbolt account you can create user profiles using your browser. See. https://www.howtogeek.com/139705/how-to-use-multiple-browser-profiles-in-any-browser/
We have an item in the backlog to solve your use case in the future: