Signing our your devices/clients includes your server – however it doesn’t remove access to your libraries for friends. Did you reclaim your server after you changed your password (access your server locally, using its local IP address from within the same network/subnet; open Settings > [Server Name] > General and click the Sign In button on that settings page; alternatively you can use a script to reclaim your server).
If you had deleted the server’s preferences.xml, this results in your server losing its unique machine identifier. Therefore Plex considers your server/libraries to be different from before – assuming your friends have not been granted access to any of the “new” ones. In that case the answer to your question is: no, there’s no means to mass-grant access to multiple friends at the same time.
