With your Permanent.org account, you can create and join an unlimited number of archives. 

To switch from your current archive to a different archive in the mobile app, navigate to your account menu by tapping the gear in the top right corner of your screen, then tap Archives.

You will be taken to your Archives list, which contains all of the archives that you are an owner or a member of along with your access role for each archive. Find the archive you wish to switch to, then tap the name.

The archive that you have selected will appear at the top of your Archives screen to indicate that you are working in it.

To navigate to a workspace in that archive, tap the hamburger icon in the top left corner of the screen, then select the workspace you wish to work in by tapping it. You can tell which archive you are inside of in this menu by looking at the archive name and profile picture at the top of the menu.