When the Currency Switcher is enabled correctly, it adds a new menu item in WordPress Admin, which is WooCommerce > Currency Switcher Options. When this doesn't occur, the most common reason is that the required Aelia Foundation Classes plugin (AFC, for short) is not installed.  

The Currency Switcher, as well as all the other Aelia plugins, are able to detect the presence of the AFC plugin, and prompt the administrator to install it when it's absent. In such case, a message like the following appears, inviting to install or activate the AFC:

Clicking on the Install or Activate button will enable the AFC plugin, and the Currency Switcher should start working normally.

What to do if the message doesn't appear?

Some 3rd party plugins suppress the messages displayed in the Admin section. When this happens, the Currency Switcher might appear to be "idle" without any apparent reason. In this case, it's still possible to install the Aelia Foundation Classes manually, as follows:

  1. Download the AFC plugin: http://bit.ly/WC_AFC_S3
  2. Install the plugin (it works like a normal plugin).
  3. Activate the AFC.

The Currency Switcher should then start working normally.