By default, Ninite installs most apps for all users on a machine. This is because most installers behave this way by default.
There are a exceptions though. The following apps only install for the current user:
Ninite Pro includes an /allusers switch you can use to force installation for all users on a machine. This feature only supports Chrome and Dropbox at the moment. We are working on adding support for other apps.
Here's an example command:
NinitePro.exe /select Chrome Dropbox Hulu Firefox /allusers
It will install Chrome and Dropbox for all users. Hulu will be installed for the current user only since /allusers does not support it yet. Firefox will be installed normally (which is for all users by default).
* Please note that Dropbox will only be installed for all users when Ninite does not detect any existing per-user Dropbox installations on the system.
These features are only available in Ninite Pro Classic.
We're working on documentation for the new Pro web interface. For now the available help for that is inline in the interface.