Hi,
This is explained in the changelog:
Obsolete options no more supported: Online/Offline, Change Services Names and Add localhost in url.
As with all hosters, for your local sites you must use VirtualHost.
See
The need for Virtual Host and
Wampserver 3 - Create or add a VirtualHost---------------------------------------------------------------
Documentation Apache -
Documentation PHP -
Documentation MySQL -
Wampserver install files & addons