HttpWatch can be installed either for your Windows account only or for everyone who uses the computer.
For a new installation, starting the installer normally installs HttpWatch for your Windows account. Setup does not normally display the Install Mode page or require administrator rights, and HttpWatch is available only when you are signed in to that account.
To make the option to install for everyone available, use either of these methods:
Setup then displays the Install Mode page. Select All Users - install for everyone on this computer:

For a new installation, neither method selects installation for everyone automatically; you still choose the option on the Install Mode page. Installing for everyone requires administrator rights. Run as administrator supplies those rights before Setup starts, while Setup requests them after you select the option when /all-users=1 is used from a non-elevated command prompt.
When updating an existing installation that is already available to everyone who uses the computer, the installer always displays the Install Mode page with All Users selected. Administrator rights are required for either choice because Setup must update or remove the existing configuration for everyone on the computer.
For unattended deployment, see Silent Install. In silent mode, /all-users=1 directly selects installation for everyone and Setup must already be running with administrator rights.