wp-admin login problems

I just propagated my domain from hostgator to bluehost.

Now at bluehost …
1. When I try to login to the admin panel of my root-domain the system does not remember my password forcing me to insert password every time I want to access my root-domain’s admin panel.
2. When I try to login to the admin panel of my sub-domain the system does not recognize my password altogether forcing me to restore password via email every time I want to access my sub-domain’s admin panel.