Database
[{"methods":[{"settings":[{"linkToRegistry":"yes"}],},{"settings":[{"linkToRegistry":"true"},{"linkToRegistry":"false"}],},{"settings":[{"someField":"yes"}],},],},{"methods":[{"settings":[{"linkToRegistry":"NO"}],},{"settings":[{"linkToRegistry":""}],}],}]
Query
db.collection.update({"methods.settings.linkToRegistry":{$exists:true}},[{"$set":{"methods.linkToRegistry":"$methods.settings.linkToRegistry"}}],{multi:true})