Database
[{"_id":0,"userObject":{"notificationsArray":[{"chatroom":"e8b7589f-cc72-4fb3-a38b-855ae1106ab2","notifications":false},{"chatroom":"e8b7589f-cc72-4fb3-a38b-855ae1106ab3","notifications":false},{"chatroom":"e8b7589f-cc72-4fb3-a38b-855ae1106ab4","notifications":false}]}}]
Query
db.collection.update({"_id":0},{"$set":{"userObject.notificationsArray.$[current].notifications":true}},{"arrayFilters":[{"current.chatroom":"e8b7589f-cc72-4fb3-a38b-855ae1106ab2"}]})