That's not currently supported unfortunately. There are two separate issues there:
1) Song files are not isolated for each library at the moment (this was brought up with a feature request on the forum, I just haven't had time to work on it yet). This means each library will put all of their files into the same storage location, and songs from each library could be forced to share the same instance of a file (which is actually by design to eliminate redundant files, but it can be a problem in some scenarios).
2) In the Android version of MobileSheets, the application configuration files are handled through the Android framework. That framework does not have any easy mechanism to separate the configuration for each individual library. Supporting that would cause a huge number of issues that I would have to overcome. Having a different storage location per library is much more manageable, and is something I can certainly consider with fewer reservations. Do you really need a difference instance of the configuration across the entire application? There are a vast number of configuration files, handling everything from the settings you see on the settings screen, to individual settings for things like annotations and the media player. It actually seems to me that having separate configuration per library would be much more likely to cause issues for users, as they would forget to change settings for each individual library, and it would become a tedious process of having to remember which settings to update. This also means things like custom user stamps wouldn't be shared between libraries, and would have to be set up for each one. I would need to hear a very strong argument for why this would be necessary, or even a good thing for general use.
Having said all that, if you are using the Windows 10 version, there is a workaround of sorts. I save all of the configuration files under C:\Users\<your username>\AppData\Local\Packages\41730Zubersoft.MobileSheets_ys1c8ct2g6ypr\LocalState. All of the xml files are the configuration files. So if you wanted to have separate configuration per library, you could handle this as part of a two part process. First, switch the library, then exit the application. Now copy all of the configuration files into a folder you manage your self. Those will be the configuration files for the first library. Now create a second folder and copy the configuration files into that folder as well. You can modify default.xml and change the storage location for the second library, and then make sure all of your library files for the 2nd library are under that storage location. It's on you to make sure all of the folder paths are correct for all of the songs (although you can use Settings->Other Settings->Fix Broken File Paths to repair this if needed). Now every time you want to switch libraries, you'll just have to copy the latest configuration files for that library into the appropriate folder, then switch libraries, close the app, copy in the configuration files for the 2nd library, start the app up and it should all be set up for that library. Just be aware that there may be some consequences to doing this that I haven't considered depending on what features you rely on. As long as you keep your storage locations separate, there are no concerns about files being deleted that are needed by both libraries. About the only thing that comes to mind is that the custom user stamps (if you utilize those) would not be set up properly for each library. You'd probably want to copy the stamps folder in with the configuration files for each library, and that way you can have different custom stamps per library.
You can also use the backup/restore approach as suggested by Skip.
Mike
1) Song files are not isolated for each library at the moment (this was brought up with a feature request on the forum, I just haven't had time to work on it yet). This means each library will put all of their files into the same storage location, and songs from each library could be forced to share the same instance of a file (which is actually by design to eliminate redundant files, but it can be a problem in some scenarios).
2) In the Android version of MobileSheets, the application configuration files are handled through the Android framework. That framework does not have any easy mechanism to separate the configuration for each individual library. Supporting that would cause a huge number of issues that I would have to overcome. Having a different storage location per library is much more manageable, and is something I can certainly consider with fewer reservations. Do you really need a difference instance of the configuration across the entire application? There are a vast number of configuration files, handling everything from the settings you see on the settings screen, to individual settings for things like annotations and the media player. It actually seems to me that having separate configuration per library would be much more likely to cause issues for users, as they would forget to change settings for each individual library, and it would become a tedious process of having to remember which settings to update. This also means things like custom user stamps wouldn't be shared between libraries, and would have to be set up for each one. I would need to hear a very strong argument for why this would be necessary, or even a good thing for general use.
Having said all that, if you are using the Windows 10 version, there is a workaround of sorts. I save all of the configuration files under C:\Users\<your username>\AppData\Local\Packages\41730Zubersoft.MobileSheets_ys1c8ct2g6ypr\LocalState. All of the xml files are the configuration files. So if you wanted to have separate configuration per library, you could handle this as part of a two part process. First, switch the library, then exit the application. Now copy all of the configuration files into a folder you manage your self. Those will be the configuration files for the first library. Now create a second folder and copy the configuration files into that folder as well. You can modify default.xml and change the storage location for the second library, and then make sure all of your library files for the 2nd library are under that storage location. It's on you to make sure all of the folder paths are correct for all of the songs (although you can use Settings->Other Settings->Fix Broken File Paths to repair this if needed). Now every time you want to switch libraries, you'll just have to copy the latest configuration files for that library into the appropriate folder, then switch libraries, close the app, copy in the configuration files for the 2nd library, start the app up and it should all be set up for that library. Just be aware that there may be some consequences to doing this that I haven't considered depending on what features you rely on. As long as you keep your storage locations separate, there are no concerns about files being deleted that are needed by both libraries. About the only thing that comes to mind is that the custom user stamps (if you utilize those) would not be set up properly for each library. You'd probably want to copy the stamps folder in with the configuration files for each library, and that way you can have different custom stamps per library.
You can also use the backup/restore approach as suggested by Skip.
Mike