how change password OSM on Fb?
Change of password on FB
You can't change password on OSM on FB. you can change your FB password and you'll still be able to access OSM.
If you want to change OSM password, it will only affect when you try to access OSM via App or Web, if you want to log in with OSM details (you can always log with your FB account details if you want to). To change this password, you need to have an e-mail configured on your account and you go to web login page and click on forget password.