HI Risheel,
If you are not managing any key/value along with user score in Storage service then I would suggest you to call the below function before inserting a document in No-SQL Storage service.
App42API.SetLoggedInUser("UserName");
Using the above function, your document will have owner attached with the inserted document. So that later on if you missed the document id from player settings, you can fetch and updated the document based on the owner.
To find/updated the document based on the owner, please have a look into this thread and let me know if you need any other assistance from our side.
Regards,
Himanshu Sharma