Hey, it seems Joplin uses "Apps/Joplin" as default to store all of my encrypted notes.
I would like to create multiple profiles for different purposes and have all of my notes stored on the same OneDrive account.
Is there a way to somehow change this default directory?
Thank you.
That's one of the limitations when using profiles with services like OneDrive, Dropbox, etc. Basically, you would need to have a separate OneDrive account for each profile.
What about using filesystem as sync target and then using google cloud? Is it possible?
With filesystem sync, you can use any syncing solution you want 
. Please keep in mind though that when it comes to mobile, the only way to make filesystem sync work on Android is to either use Syncthing (or possibly 3rd party wrappers that do local two-way sync for the big cloud sync services), and then on iOS you can't use filesystem sync at all.
I have two apps for Android that can synchronize the Joplin folder on the phone with a Joplin folder pretty much anywhere.
One of them comes from the Google Play app store and is simply called foldersync.
The other is called roundsync. It is hosted on GitHub and I can give you the direct link if you want it?
Round-Sync is an implementation of an open source application called rclone.
Rclone supports over 50 Cloud providers and can synchronize one way two ways either manually or on a schedule. It can sync with Windows and Linux and Mac on a Lan.