Usually I\'m using this code
Member member = ctx.Members.Find(id);
member.Name = txtName.Text;
ctx.Entry(member).State = EntityState.Modified;
ctx.SaveChanges();
If you are using change tracking then proxy objects listen to properties changes and update context automatically which is quite useful in mvvm where you just bind properties to controls and don't have to write code behind to update context
If you are not using change tracking (for example when you are dealing with large amount of entities) you have to update context yourself