Hello Salomaha,
Thank you very much for sharing with us your inquiries. I'm very glad to assist you with these questions. From what I understood, you would like to know if your cloud storage goes on each of the account you set up on your device and also what happens if your reset your device, correct? Well, you can have multiple accounts on the device but you can set your cloud storage on only one account which will be the primary account in this case as you can not have two Microsoft accounts on one device. Secondly, resetting the device doesn't affect your account or the cloud storage. When you reset the device, and reenter your Microsoft account ( Primary account) everything will back up on the device.
I hope I answered your preoccupation. If you have any other questions, we would like to assist.
Thank you again for posting.