Database
[{"_id":ObjectId("61a8e433648e1963ae7358be"),"myArray":[{"description":"test","starting":null,"ending":null,"_id":ObjectId("61d6e320520fac65775a7ba8")},{"description":"test 2","starting":null,"ending":null,"_id":ObjectId("61d6e320520fac657812991a")},],}]
Query
db.collection.update({"_id":ObjectId("61a8e433648e1963ae7358be"),"myArray._id":ObjectId("61d6e320520fac65775a7ba8")},{"$set":{"myArray.$.description":"Updated Description"}})