UserManager.FindAsync to use custom Userstore's FindByIdAsync method instead of FindByNameAsync

I'm using Identity Framework. When I login to my app, the appUser retrieves the UserManager as follow:

Patient patient = await UserManager.FindAsync(model.Id, model.Password);

As I understand from debugging, UserManager.FindAsync uses the FindByNameAsync(string userName) from the UserStore (I have a custom UserStore).

The question is: How to tell UserManager.FindAsync to use the FindByIdAsync method of my custom UserStore instead of FindByNameAsync?

Do I need to also write a custom UserManager?

Thanks in advance.

You can override the method in a custom UserManager

public class ApplicationUserManager : UserManager<AppUser, string>
{
     public override async Task<AppUser> FindAsync(string id, string password)
     {
         var user = await FindByIdAsync(id).WithCurrentCulture();
         if (user == null)
         {
             return null;
         }
         return await CheckPasswordAsync(user, password).WithCurrentCulture() ? user : null;
     }   
}