How to change Lots in Manufacturing Order
There are different ways of how to change Lots for Bill of Material in Manufacturing Order in version Odoo 10 and 11.
For version Odoo 11 it should first click button "unlock" at Manufacturing Order screen -> Edit -> it would be able to make changes.
To save that changes- click save and "lock". Button "unlock" can be used only for user that authorized as Manufacturing Manager
Here is video of how it can be done at Version 10